Lymphatic-type "Angiosarcoma" With Prominent Lymphocytic Infiltrate.

We report 21 cases of a distinctive and unique vascular tumor which we propose to be a pure lymphatic-type angiosarcoma characterized by architectural and growth characteristics of angiosarcoma, cytologic, and immunohistochemical features of lymphatic differentiation, a prominent lymphocytic infiltrate, and variable nuclear grade. Patients included 12 males and 9 females with a median age of 65 years (range: 32 to 95 y). Tumors involved the head and neck (n=11), lower extremities (n=5), trunk (n=4), and upper extremity (n=1) and were located superficially in the dermis and/or subcutis. Tumors were designated "low grade" (n=10) when the nuclear grade was low, and vascular channel formation was evident throughout but with multilayering of endothelium within the vessels. Cases were designated "high grade" (n=11) when nuclei appeared higher grade with more rounded contours and prominent nucleoli and when solid areas predominated over vascular channel formation. A striking feature of both groups was the presence of a dense, lymphocytic infiltrate with occasional germinal center formation. All cases strongly and diffusely expressed at least 1 lymphatic marker (21/21) with podoplanin (17/19) and Prox-1 (11/11) more commonly expressed than LYVE-1 (5/10). No consistent molecular alteration was identified. Follow-up on 17 patients (median: 41 mo, mean: 54 mo) showed 10 patients were alive without disease, 5 were alive with disease, 1 died of other cause, and 1 died of disease. Local recurrence developed in 9 cases and metastasis in 2 cases, although neither correlated with grade as defined. On the basis of clinical follow-up to date, the natural history of lymphatic-type angiosarcoma appears to be more favorable than other forms of cutaneous angiosarcoma.

Intrasinusoidal Spread of Hepatic Epithelioid Hemangioendothelioma: Implications for the Diagnosis in Minimal Samples.

Epithelioid hemangioendothelioma (EHE) is an angiocentric tumor that, when arising in liver, is centered around hepatic/portal veins. However, EHE cells can also track along sinusoids, which is not well recognized or studied. We identified 18 cases of hepatic EHE and 6 nonhepatic EHEs. For all cases, we recorded EHE multifocality and maximum size. When tumor cells were identified apart from the main mass, we recorded their location, maximum distance from the main tumor, density per high-power field, and cytomorphology. Immunohistochemical staining for CAMTA1, ERG, and CAM5.2 was performed on all cases. Lesional cells were present apart from the main mass in 17 of 18 (94%) liver cases, always within sinusoids and occasionally (4/17, 24%) in central veins. They appeared intensely hyperchromatic with vaguely cerebriform nuclei and multinucleation in 6 (35%) of cases. CAMTA1 and ERG positivity was seen in all 17 cases. Two cases (12%) demonstrated focal CAM5.2 positivity. Sinusoidal EHE cells ranged from 0.1 to 0.8 cm away from the main tumor. There were no statistically significant associations between histologic findings and patient outcome. In the 6 nonhepatic cases, tumor cells did not extend beyond the main EHE. Lesional cells in hepatic EHE often extend beyond the main lesion into sinusoids, where they demonstrate an unusual, somewhat distinctive morphology. Care should be taken to identify such cells in limited biopsies; immunohistochemistry for CAMTA1, a specific and sensitive marker for EHE, can be confirmatory.

Histiocyte-rich rhabdomyoblastic tumor: rhabdomyosarcoma, rhabdomyoma, or rhabdomyoblastic tumor of uncertain malignant potential? A histologically distinctive rhabdomyoblastic tumor in search of a place in the classification of skeletal muscle neoplasms.

Skeletal muscle tumors are traditionally classified as rhabdomyoma or rhabdomyosarcoma. We have identified an unusual adult rhabdomyoblastic tumor not clearly corresponding to a previously described variant of rhabdomyoma or rhabdomyosarcoma, characterized by a very striking proliferation of non-neoplastic histiocytes, obscuring the underlying tumor. Ten cases were identified in nine males and one female with a median age of 43 years (range 23-69 years). Tumors involved the deep soft tissues of the trunk (N = 4), lower limbs (N = 4), and neck (N = 2). Tumors were well-circumscribed, nodular masses, frequently surrounded by a fibrous capsule containing lymphoid aggregates and sometimes calcifications. Numerous foamy macrophages, multinucleated Touton-type giant cells, and sheets/fascicles of smaller, often spindled macrophages largely obscured the underlying desmin, MyoD1, and myogenin-positive rhabdomyoblastic tumor. Cases were wild type for MYOD1 and no other mutations or rearrangements characteristic of a known subtype of rhabdomyoma or rhabdomyosarcoma were identified. Two of four cases successfully analyzed using a next-generation sequencing panel of 170 common cancer-related genes harbored inactivating NF1 mutations. Next-generation sequencing showed no gene fusions. Clinical follow (nine patients; median 9 months; mean 23 months; range 3-124 months) showed all patients received wide excision; four patients also received adjuvant radiotherapy and none received chemotherapy. At the time of last follow-up, all patients were alive and without disease; no local recurrences or distant metastases occurred. We hypothesize that these unusual tumors represent rhabdomyoblastic tumors of uncertain malignant potential. Possibly over time they should be relegated to a new category of skeletal muscle tumors of intermediate (borderline) malignancy.

Fibrous hamartoma of infancy: a clinicopathologic study of 145 cases, including 2 with sarcomatous features.

Fibrous hamartoma of infancy is a rare soft tissue lesion of infants and young children with characteristic triphasic morphology, which typically occurs in the axilla and less commonly in other locations. We reviewed 145 cases of fibrous hamartoma of infancy from our consultation archives. Cases occurred in 106 males and 39 females (mean age-15 months; range-birth to 14 years), and involved both typical sites (eg, axilla/back/upper arm) (n=69) and unusual locations (n=76). Six were congenital. The tumors presented as subcutaneous masses and ranged from 0.4 to 17 cm (mean 3 cm). All displayed triphasic morphology, but varied widely in the relative percentages of fat, fibroblastic fascicles, and primitive mesenchyme. Hyalinized zones with cracking artifact, mimicking giant cell fibroblastoma, were present in a 44 (30%) of cases; however FISH for PDGFB gene rearrangement was negative in five tested cases. In addition to classical fibrous hamartoma of infancy, two lesions contained large sarcomatous-appearing foci with high cellularity, high nuclear grade, and brisk mitotic activity. One occurred in a 10-month-old female as a new mass in a congenital fibrous hamartoma of infancy; the other occurred as a leg mass in a 6-year-old male. ETV6 gene rearrangement was negative in the tumor from the 10-month-old female. Genomic microarray (OncoScan) showed normal molecular karyotype in eight tested cases, whereas the two tumors with sarcomatous features showed a hyperdiploid/near tetraploid molecular karyotype with copy neutral loss of heterozygosity of chromosomes 1p and 11p, and loss of 10p, chromosome 14, and a large portion of chromosome 22q (22q11.23q13.33), respectively. Follow-up (52 patients; range: 1-208 months, median: 8 months) showed only two local recurrences and no metastases. Extensive local disease in the 10-month-old female with sarcomatous-appearing fibrous hamartoma of infancy necessitated forequarter amputation. In summary, our study confirms the classic clinicopathologic features, including the triphasic morphologic appearance of most cases. In contrast to earlier studies, our series illustrates a broader histologic spectrum than previously appreciated, including its close resemblance to giant cell fibroblastoma in one quarter of cases and the rare presence of 'sarcomatous' areas, the latter providing evidence that these are complex neoplasms rather than hamartomas.

MDM2 and CDK4 Immunohistochemistry: Should It Be Used in Problematic Differentiated Lipomatous Tumors?: A New Perspective.

Although most cases of atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDL) can be diagnosed solely on the basis of histologic features, those lacking diagnostic histologic features require ancillary studies for accurate classification. Fluorescent in situ hybridization (FISH) for amplification of MDM2 has been considered the gold standard for diagnosis in these situations. Immunostaining for MDM2 and/or CDK4 has been adopted as a surrogate method because of its high concordance rate with FISH and lower cost. However, studies examining the concordance of the 2 methods have been based preferentially on cases in which the diagnosis could be established histologically. No study has explored the concordance between the 2 methods in histologically ambiguous cases or in cases in which the diagnosis of ALT/WDL is not apparent after a review of all slides. To address this, we performed immunostaining for MDM2 and CDK4 on 183 well-differentiated lipomatous tumors that could not be diagnosed on purely histologic grounds and that were, therefore, subjected to FISH analysis. These included ALT/WDLs (n=56), lipomas (n=96), and lipoma variants (n=31). Staining for MDM2 and CDK4 was noted in 25/56 and 23/56 ALT/WDL, respectively, giving a sensitivity of 45% and 41% and a specificity of 98% and 92%. Staining was noted exclusively in the nuclei of atypical cells and not in the nuclei of adipocytes. Staining for MDM2 and CDK4 occurred in 2/125 and 10/117 benign lipomatous lesions, respectively. False-positive staining was equivalent in intensity to ALT/WDL. We conclude that MDM2 and CDK4 staining is a relatively insensitive method for diagnosing ALT/WDL in cases that are histologically ambiguous, as staining is restricted to neoplastic cells with atypia that are underrepresented in these cases. Therefore, in cases like ours that closely simulate clinical practice, FISH is the more reliable and cost-effective option.

TGFBR3 and MGEA5 rearrangements are much more common in "hybrid" hemosiderotic fibrolipomatous tumor-myxoinflammatory fibroblastic sarcomas than in classical myxoinflammatory fibroblastic sarcomas: a morphological and fluorescence in situ hybridization study.

Myxoinflammatory fibroblastic sarcoma (MIFS) is a rare low-grade sarcoma that most often involves the distal extremities of adults. Some MIFSs have been reported to show TGFBR3 and MGEA5 rearrangements. TGFBR3 and MGEA5 rearrangements have also been reported in hemosiderotic fibrolipomatous tumor (HFLT), in pleomorphic hyalinizing angiectatic tumor (PHAT), and in rare tumors allegedly showing features of both HFLT and MIFS (hybrid HFLT-MIFS). These findings have led to speculation that HFLT, MIFS, PHAT, and hybrid HFLT-MIFS are closely related; however, areas resembling HFLTs are only very rarely encountered in previous series of MIFSs. We studied classic examples of these tumors with the goal of clarifying the relationship between MIFS and HFLT-MIFS. Cases of MIFS (n=31), hybrid HFLT-MIFS (n=8), PHAT (n=2), HFLT (n=1), and undifferentiated pleomorphic sarcoma (n=4) were retrieved from our archives, and the diagnoses were verified by 5 soft tissue pathologists. Using previously validated break-apart fluorescence in situ hybridization probes, we analyzed for TGFBR3 and MGEA5 rearrangements. Only 2 of 31 MIFSs harbored MGEA5 rearrangements; all lacked TGFBR3 rearrangements. Six of 8 hybrid HFLT-MIFSs harbored rearrangements of TGFBR3 and/or MGEA5. Both PHATs were positive for rearrangements of TGFBR3 and/or MGEA5. The HFLT was positive for rearrangements of both TGFBR3 and MGEA5. All undifferentiated pleomorphic sarcomas with focal myxoid change were negative. We conclude that (1) TGFBR3 and/or MGEA5 rearrangements are much more common in hybrid HFLT-MIFSs than in classic MIFSs, (2) HFLTs and MIFSs may be unrelated lesions, and (3) hybrid HFLT-MIFSs most likely represent HFLTs with sarcomatous progression, rather than tumors strictly related to classic MIFSs.

Physician scientist research pathway leading to certification by the American Board of Pathology.

In 2014, the American Board of Pathology, in response to the pathology community, approved a physician scientist research pathway (PSRP). This brief report summarizes the history of and objectives for creating the physician scientist research pathway and the requirements of the American Board of Pathology for the certification of physician scientist research pathway trainees.

Epithelioid Schwannomas: An Analysis of 58 Cases Including Atypical Variants.

The histologic features and outcome of 58 cases of epithelioid schwannoma were studied to determine the significance of atypical histologic features. Cases were retrieved from personal consultation files from 1999 to 2013. Patients (31 male and 26 female patients) ranged in age from 14 to 80 years (median, 38 y). Two patients had schwannomatosis 1. Tumors developed in the dermis/subcutis (n=56) or muscle (n=2) of the upper extremity (34.5%), lower extremity (34.5%), thorax/abdomen/back (18%), and less common anatomic locations including the scalp, neck, lip, and breast. They ranged in size from 0.25 to 4.5 cm (median, 2.0 cm). Typically circumscribed and surrounded by a perineurium, they comprised single or small groups of epithelioid schwann cells with a moderate amphophilic cytoplasm and occasional nuclear pseudoinclusions. Stroma varied from myxoid to hyalinized, often with thick-walled vessels (55 cases). Mitotic rate ranged from 0 to 9 mitoses/10 high-power field (HPF) (2.37 mm) in the most active areas (mean, 2 to 3 mitoses/10 HPFs). Thirteen cases (22%) were "atypical," defined by a high mitotic rate (≥3 mitoses per 10 HPFs) and nuclear size variation (≥3:1). All (56/56) expressed S100 protein; type IV collagen invested groups or individual cells (16/17). Melanoma markers were negative, except for melan A (1 case). Follow-up in 39 patients (median, 78 mo; range, 6 to 174 mo) indicated that 31 (79%) were alive without disease (including 9/13 atypical cases; median, 78 mo), 7 (18%) were alive with unknown status, and 1 patient had died of unrelated causes. One tumor recurred, but none metastasized. Epithelioid schwannomas, even those with atypical features, are benign and do not constitute a histologic continuum with epithelioid malignant peripheral nerve sheath tumors, which typically occur in deep soft tissues and have more anaplastic features.

Physician Scientist Research Pathway Leading to Certification by the American Board of Pathology.

In 2014, the American Board of Pathology, in response to the pathology community, approved a physician scientist research pathway. This brief report summarizes the history of and objectives for creating the physician scientist research pathway and the requirements of the American Board of Pathology for the certification of physician scientist research pathway trainees.

MDM2 Amplification in Problematic Lipomatous Tumors: Analysis of FISH Testing Criteria.

To discriminate lipomas from atypical lipomatous tumor/well-differentiated liposarcoma (ALT/WDL) we perform fluorescence in situ hybridization (FISH) for MDM2 amplification in several problematic situations: "lipomas" >10 cm, lesions with equivocal atypia, recurrent "lipomas," all retroperitoneal/pelvic/abdominal "lipomas", and in cases not fitting the above criteria but having worrisome clinical or radiologic features. To ascertain the validity of these criteria, we have reviewed our experience with 301 consecutive differentiated lipomatous tumors in which the diagnosis of ALT could not be established on the basis of histologic sections and in which FISH was performed on the basis of the above criteria. The final diagnosis was based on MDM2 amplification status. Given the nature of this study to evaluate difficult lesions, most cases included (74%) were received in consultation. This enhanced our study series for borderline cases, and the data presented may not be generalizable to adipocytic tumors seen outside a subspecialty setting. Of 301 cases, 108 proved to be ALT/WDL (36%). The most common test indication was size >10 cm (n=187), followed by equivocal atypia (n=145), retroperitoneal/pelvic/abdominal location (n=86), recurrence (n=33), and clinical concern (n=12). Of the tumors >10 cm, 68 (36%) proved to be ALT/WDL, whereas the remainder were interpreted as lipoma or its variants (eg, spindle cell or pleomorphic lipoma). The 2 groups did not differ statistically in size, although ALTs consistently occurred in patients above 50 years of age. Of the cases with equivocal atypia, 72 (50%) proved to be ALT/WDL. Those in the retroperitoneum/abdomen/pelvis were ALT/WDL in 30 cases (35%), and those that had recurred were ALT in 18 cases (55%). Recurrence, atypia, and having multiple indications for testing were more common in ALT than in benign lesions (P=0.02, 0.0001, 0.0012, respectively). No ALT/WDL occurred in the hands and feet, and only a single ALT/WDL was superficial (1 ALT/WDL vs. 60 lipoma/spindle cell or pleomorphic lipoma). Small (<10 cm) retroperitoneal tumors without additional features were always benign (n=9). On the basis of our results, FISH testing is recommended for: (1) recurrent lesions; (2) deep extremity lesions that are >10 cm in patients over 50 years of age; (3) in cases with equivocal atypia; (4) in lesions of the retroperitoneum/pelvis/abdomen, and in special clinical situations as directed by treating clinicians. Testing is low yield in superficial lesions, in small extremity lesions without additional indicators for testing, in large extremity lesions without additional features in patients under the age of 50, and in lesions arising in the hands/feet. More evidence is needed regarding testing in small retroperitoneal lesions without additional features. By adopting these criteria, we could have avoided testing 74 cases, missing a single superficial ALT/WDL.

Myofibromas with atypical features: expanding the morphologic spectrum of a benign entity.

Typical myofibromas are biphasic tumors composed of a central zone of immature spindled to rounded cells arranged in a pericytic pattern and a peripheral zone of myoid nodules. Central necrosis is occasionally seen. A small but undefined subset of myofibromas displays atypical features that may lead to a misdiagnosis of sarcoma. To more completely characterize these tumors and define their behavior, we analyzed our experience with myofibromas having 1 or more atypical features including hypercellularity, absent or inconspicuous, poorly demarcated myoid nodules, infiltrative growth pattern, and perineural invasion. Of 266 cases of myofibromas, 24 cases were retrieved on the basis of pathology reports in which atypical features were mentioned. The tumors presented in 16 male and 8 female individuals (mean age 17 y; range, 2 wk to 62 y) as masses of variable size (mean 3.0 cm; range, 1.5 to 6.5 cm). Fourteen cases arose on the head and neck and 10 cases on the limbs. The referring or suspected diagnosis was sarcoma in 8 cases. The tumors were typically more cellular than ordinary myofibroma with levels of cellularity similar to that expected in fibrosarcoma (22/24). In addition, they displayed inconspicuous, loosely cohesive (22/24) or absent myoid nodules (2/24), infiltrating borders (19/24), intravascular growth (5/24), and perineural invasion/nerve entrapment (6/24). The mean mitotic rate was 5 mitoses/10 high-power fields, but no tumor showed significant cytologic atypia. The tumors were positive for actins (11/11) and CD34 (2/8). Follow-up in 14 patients revealed no distant metastases. We conclude that a small subset of myofibromas shows atypical features that complicate the diagnosis but do not adversely affect outcome.

Superficial CD34-positive fibroblastic tumor: report of 18 cases of a distinctive low-grade mesenchymal neoplasm of intermediate (borderline) malignancy.

Fibroblastic mesenchymal tumors show a spectrum of biological behavior, from benign to fully malignant. We report our experience of two decades with a distinctive, previously undescribed low-grade fibroblastic tumor of the superficial soft tissues. Eighteen cases were identified within our consultation files, previously coded as 'low-grade sarcoma, not further classified' and 'malignant fibrous histiocytoma, low grade'. The tumors occurred in adults (median age 38 years, range 20-76 years) of either sex (10 males and 8 females), ranged in size from 1.5 to 10 cm (mean 4.1 cm), and were confined to the superficial soft tissues of the thigh (N=5), knee (N=2), and other sites. Histological features included a fascicular growth pattern of the neoplastic spindled cells with striking, often bizarre cellular pleomorphism and variably prominent nucleoli. Necrosis was seen in one case. All cases showed strong, diffuse CD34 positivity and 68% of tested cases demonstrated focal cytokeratin expression. Desmin, ERG, FLI-1, smooth muscle actin, and S100 protein were negative. TP53 overexpression was absent. Fluorescence in-situ hybridization studies for TGFBR3 and/or MGEA5 rearrangements were negative in all tested cases. Clinical follow-up was available in 13 patients (median duration of 24 months; range 1-104 months). Twelve of 13 patients had no disease recurrence. One patient had regional lymph node metastases, 7 years after incomplete excision of the primary tumor. All patients are currently alive and disease free. The unique clinicopathological features of superficial CD34-positive fibroblastic tumor define them as a novel subset of low-grade fibroblastic neoplasms, best considered to be of borderline malignancy.

The General Surgeon's quandary: atypical lipomatous tumor vs lipoma, who needs a surgical oncologist?

BACKGROUND: Differentiating large lipomas from atypical lipomatous tumors (ALT) is challenging, and preoperative management guidelines are not well defined. The diagnostic ambiguity leads many surgeons to refer all patients with large lipomatous masses to an oncologic specialist, perhaps unnecessarily. STUDY DESIGN: In this retrospective cohort study of patients with nonretroperitoneal lipomatous tumors, preoperative characteristics discernible without invasive diagnostic procedures were evaluated for diagnostic predictive value. RESULTS: We identified 319 patients (256 with lipomas, 63 with ALTs) treated between 1994 and 2012. Patients with ALTs were older (60.5 vs 53.5 years, p < 0.0001), had larger tumors (16.0 vs 8.3 cm, p < 0.0001), had tumors more often located on an extremity (88.9% vs 60.5% torso, p < 0.0001), and more frequently had a history of previous operations at the same site, exclusive of excision leading to diagnosis and referral (20.6% vs 5.9%, p = 0.001). Local recurrence was observed in 2 patients with lipomas (0.8%) vs 14 with ALTs (22.6%, p < 0.0001). No patients with ALTs developed distant metastases or disease-specific mortality, with a median follow-up of 27.4 months (range 0 to 164.6 months). On multivariate analysis, age ≥ 55 years, tumor size ≥ 10 cm, extremity location, and history of previous resections were predictors for diagnosis of ALT (p < 0.05). CONCLUSIONS: Characteristics of lipomatous masses associated with a diagnosis of ALT include patient age ≥ 55 years, tumor size ≥ 10 cm, previous resection, and extremity location (vs torso). These easily identifiable traits may guide surgical management or referral to a specialist.

Fibrosarcoma-like lipomatous neoplasm: a reappraisal of so-called spindle cell liposarcoma defining a unique lipomatous tumor unrelated to other liposarcomas.

The term "spindle cell liposarcoma" has been applied to liposarcomas (LPSs) composed predominantly or exclusively of spindled cells. These tumors have been considered variants of well-differentiated LPS (WDL), myxoid LPS, and spindle cell lipoma, suggesting that this is a heterogenous group of lesions. Using strict morphologic criteria and molecular and immunohistochemical analyses, we have identified a homogenous group of spindle cell lipomatous tumors, histologically and genetically distinct from other forms of LPS, which we have called "fibrosarcoma-like lipomatous neoplasm." Cases classified as "spindle cell LPS" or "low-grade LPS with spindle cell features" were reviewed. Final selection criteria included: (1) an exclusive low-grade spindle cell component resembling fibrosarcoma; (2) a mixture of bland fibroblastic cells resembling the preadipocyte and early-adipocyte stage of embryonic fat; and (3) molecular-genetic analysis that excluded other forms of lipomatous tumors. Of the initial 25 cases identified, comparative genomic hybridization (CGH) was uninformative in 2 cases; 5 were reclassified as WDL on the basis of molecular data (MDM2 amplification) and 6 as spindle cell lipoma (CGH profiles with a few gains and losses including a constant loss of chromosome 13 and frequent losses of chromosomes 16 and 6). The 12 remaining cases showed flat CGH profiles; of these cases, 11 were negative for DDIT3 gene rearrangements, and 1 result was uninterpretable. Patients ranged in age from 15 to 82 years (mean 50 y); male patients were affected slightly more often (7:5). Tumors arose in the deep (6) and superficial (3) soft tissue of the groin (4), buttock (3), thigh (2), flank (1), shoulder (1), and paratesticular tissue (1) and ranged in size from 2 to 20 cm (mean 7.5 cm). Clinical follow-up in 11 patients (9 mo to 20 y; mean 68 mo) showed no recurrences or metastases. As defined above, "fibrosarcoma-like lipomatous neoplasm" is a unique lipomatous tumor that should be distinguished from WDL/(low-grade) dedifferentiated LPS and myxoid LPS on combined histologic/molecular features because of its better prognosis.

PHF1 rearrangements in ossifying fibromyxoid tumors of soft parts: A fluorescence in situ hybridization study of 41 cases with emphasis on the malignant variant.

Ossifying fibromyxoid tumor of soft parts (OFMT) is a rare soft tissue neoplasm of uncertain differentiation. Very recently recurrent rearrangements of the PHF1 gene have been reported in OFMT, including typical, atypical, and malignant variants. We sought to validate and extend these findings in a larger series of well-characterized OFMT, in particular malignant variants. Slides and blocks from 41 OFMT were retrieved, rereviewed, and classified as typical, atypical, and malignant using previously published criteria. Interphase fluorescence in situ hybridization (FISH) was performed on paraffin-embedded sections of each case using a break-apart probe strategy, with direct-labeled FISH probes designed from bacterial artificial chromosomes. The 41 tumors occurred in 23 men and 18 women with a mean age of 55 years and involved the head and neck, trunk, and upper and lower limbs. The tumors were classified as typical (n=14), atypical (n=6) and malignant (n=21). PHF1 rearrangements were detected in 20 of 41 cases (49%) including 43% typical, 50% atypical, and 52% malignant cases. The results of our study confirm previous findings, with PHF1 rearrangements present in nearly 50% of OFMT, including roughly similar percentages of typical, atypical, and malignant tumors. These results support our previous hypothesis that OFMT might represent a translocation-associated tumor, underscore the likely importance of PHF1 rearrangements in the pathogenesis of these lesions, confirm the relationship between typical and malignant OFMT, and suggest a role for PHF1 FISH in the diagnosis of morphologically challenging cases.

Soft tissue chordomas: a clinicopathologic analysis of 11 cases.

Soft tissue chordomas (STCs) have never been systematically studied because of their rarity and the difficulty in separating them from similar-appearing lesions. Using brachyury to confirm the diagnosis, we have analyzed our experience with 11 cases. Cases coded as "chordoma" or "parachordoma" were retrieved from institutional and consultation files (1989 to 2011) and were excluded from further analysis if they arose from the bone or in a patient with previous axial chordoma. Eleven of 27 cases met inclusion criteria. Patients (8 male; 3 female) ranged in age from 13 to 71 years (mean 44 y). Tumors were located on the buttock (n=2), wrist (n=2), leg (n=2), toe (n=1), thumb (n=1), ankle (n=1), shoulder (n=1), and chest wall (n=1), ranged in size from 0.5 to 10.9 cm (mean 5.3 cm), and consisted of cords and syncytia of spindled/epithelioid cells with vacuolated eosinophilic cytoplasm and a partially myxoid background. Tumors expressed brachyury (10/10), 1 or more cytokeratins (11/11), and S100 protein (10/11). Follow-up information was available for 10 patients (69 mo; range, 2 to 212 mo). Most (n=6) were alive without disease, 2 developed local recurrence and lung metastases, and 1 developed lung metastasis only. One died with unknown disease status. STCs are histologically identical to osseous ones, but differ in their greater tendency to occur in distal locations where small size and surgical resectability result in better disease control. The existence of STC implies that notochordal remnants are not a prerequisite for chordoma development.

Cutaneous and subcutaneous pleomorphic liposarcoma: a clinicopathologic study of 29 cases with evaluation of MDM2 gene amplification in 26.

Pleomorphic liposarcoma (PL) is an uncommon form of liposarcoma that rarely occurs in the skin and subcutis. As its behavior in this setting is incompletely characterized, we undertook a study of a series of superficial PLs, defined as those arising or based primarily in the dermis and/or subcutis without involvement of deep structures. In addition, MDM2 gene amplification, a diagnostic signature of well-differentiated/dedifferentiated liposarcoma (WDL/DL), was evaluated to address the recent observation that this gene is amplified within PL-like areas in DL. PLs were obtained from institutional and consultation files (n=29). Cases were evaluated with respect to age, sex, location (dermis, dermis and subcutis, subcutis), size, predominant pattern (pleomorphic spindled or epithelioid), extent of lipogenic differentiation, and tumor necrosis. MDM2 amplification was analyzed using FISH on formalin-fixed, paraffin-embedded material in 26 cases. Patients ranged in age from 5 to 93 years (M:F=1.4:1). Tumors were located on the extremity (n=15), trunk (n=7), and head and neck (n=7) and involved the dermis (n=4), dermis and subcutis (n=10), and subcutis (n=15). Tumor size ranged from 0.8 to 15 cm (median=2 cm). All were mitotically active high-grade sarcomas [FNCLCC grade 2 (n=23) or 3 (n=6)] with either a pleomorphic spindled (n=24) or an epithelioid pattern (n=5) with variable extent of lipogenic differentiation [<25% (n=15), 25% to 50% (n=9), >50% (n=5)]. Necrosis was present in 3 cases. MDM2 gene amplification was present in 3 of 26 cases. Follow-up information in 24 cases (range=1 to 192 mo; median=48 mo; mean=59 mo) revealed local recurrences (4/24) but no metastasis or death from disease. We conclude that cutaneous and subcutaneous PLs, despite their high grade, have a much more favorable outcome compared with their deep-seated counterparts, most likely attributed to their small size and superficial location. The low incidence of MDM2 gene amplification in our series indicates that most superficial PLs are unrelated to WDL/DL. PL likely evolves by way of more than 1 molecular pathway.

Anatomic tumor location influences the success of contemporary limb-sparing surgery and radiation among adults with soft tissue sarcomas of the extremities.

PURPOSE: To examine the influence of anatomic location in the upper extremity (UE) vs. lower extremity (LE) on the presentation and outcomes of adult soft tissue sarcomas (STS). METHODS AND MATERIALS: From 2001 to 2008, 118 patients underwent limb-sparing surgery (LSS) and external beam radiotherapy (RT) with curative intent for nonrecurrent extremity STS. RT was delivered preoperatively in 96 and postoperatively in 22 patients. Lesions arose in the UE in 28 and in the LE in 90 patients. Patients with UE lesions had smaller tumors (4.5 vs. 9.0 cm, p < 0.01), were more likely to undergo a prior excision (43 vs. 22%, p = 0.03), to have close or positive margins after resection (71 vs. 49%, p = 0.04), and to undergo postoperative RT (32 vs. 14%, p = 0.04). RESULTS: Five-year actuarial local recurrence-free and distant metastasis-free survival rates for the entire group were 85 and 74%, with no difference observed between the UE and LE cohorts. Five-year actuarial probability of wound reoperation rates were 4 vs. 29% (p < 0.01) in the UE and LE respectively. Thigh lesions accounted for 84% of the required wound reoperations. The distribution of tumors within the anterior, medial, and posterior thigh compartments was 51%, 26%, and 23%. Subset analysis by compartment showed no difference in the probability of wound reoperation between the anterior and medial/posterior compartments (29 vs. 30%, p = 0.68). Neurolysis was performed during resection in (15%, 5%, and 67%, p < 0.01) of tumors in the anterior, medial, and posterior compartments. CONCLUSIONS: Tumors in the UE and LE differ significantly with respect to size and management details. The anatomy of the UE poses technical impediments to an R0 resection. Thigh tumors are associated with higher wound reoperation rates. Tumor resection in the posterior thigh compartment is more likely to result in nerve injury. A better understanding of the inherent differences between tumors in various extremity sites will assist in individualizing treatment.

Identification of a disease-defining gene fusion in epithelioid hemangioendothelioma.

Integrating transcriptomic sequencing with conventional cytogenetics, we identified WWTR1 (WW domain-containing transcription regulator 1) (3q25) and CAMTA1 (calmodulin-binding transcription activator 1) (1p36) as the two genes involved in the t(1;3)(p36;q25) chromosomal translocation that is characteristic of epithelioid hemangioendothelioma (EHE), a vascular sarcoma. This WWTR1/CAMTA1 gene fusion is under the transcriptional control of the WWTR1 promoter and encodes a putative chimeric transcription factor that joins the amino terminus of WWTR1, a protein that is highly expressed in endothelial cells, in-frame to the carboxyl terminus of CAMTA1, a protein that is normally expressed only in brain. Thus, CAMTA1 expression is activated inappropriately through a promoter-switch mechanism. The gene fusion is present in virtually all EHEs tested but is absent from all other vascular neoplasms, demonstrating it to be a disease-defining genetic alteration. A sensitive and specific break-apart fluorescence in situ hybridization assay was also developed to detect the translocation and will assist in the evaluation of this diagnostically challenging neoplasm. The chimeric WWTR1/CAMTA1 transcription factor may represent a therapeutic target for EHE and offers the opportunity to shed light on the functions of two poorly characterized proteins.