Clinical features and outcomes of young patients with low-grade non-rhabdomyosarcoma soft tissue sarcomas treated with a risk-based strategy: A report from Children's Oncology Group study ARST0332.

BACKGROUND: In retrospective analyses, the Pediatric Oncology Group [POG) and the Federation National des Centres de Lutte Contre le Cancer (FNCLCC) histologic grade predict outcome in pediatric non-rhabdomyosarcoma soft tissue sarcoma (NRSTS), but prospective data on grading, clinical features, and outcomes of low-grade NRSTS are limited. METHODS: We analyzed patients less than 30 years of age enrolled on Children's Oncology Group (COG) study ARST0332 (NCT00346164) with POG grade 1 or 2 NRSTS. Low-risk patients were treated with surgery alone. Intermediate-/high-risk patients received ifosfamide/doxorubicin and radiotherapy, with definitive resection either before or after 12 weeks of chemoradiotherapy. RESULTS: Estimated 5-year event-free and overall survival were 90% and 100% low risk (n = 80), 55% and 78% intermediate risk (n = 15), and 25% and 25% high risk (n = 4). In low-risk patients, only local recurrence was seen in 10%; none with margins greater than 1 mm recurred locally. Sixteen of 17 intermediate-/high-risk patients who completed neoadjuvant chemoradiotherapy underwent gross total tumor resection, 80% with negative margins. Intermediate-/high-risk group events included one local and seven metastatic recurrences. Had the FNCLCC grading system been used to direct treatment, 29% of low-risk (surgery alone) patients would have received radiotherapy ± chemotherapy. CONCLUSIONS: Most low-risk patients with completely resected POG low-grade NRSTS are successfully treated with surgery alone, and surgical margins greater than 1 mm may be sufficient to prevent local recurrence. Patients with intermediate- and high-risk low-grade NRSTS have outcomes similar to patients with high-grade histology, and require more effective therapies. Use of the current FNCLCC grading system may result in overtreatment of low-risk NRSTS curable with surgery alone.

The Pathologic Diagnosis of Pediatric Soft Tissue Tumors in the Era of Molecular Medicine: The Sarcoma Pediatric Pathology Research Interest Group Perspective.

CONTEXT.­: Pediatric soft tissue tumors are one of the areas of pediatric pathology that frequently generate consult requests. Evolving classification systems, ancillary testing methods, new treatment options, research enrollment opportunities, and tissue archival processes create additional complexity in handling these unique specimens. Pathologists are at the heart of this critical decision-making, balancing responsibilities to consider expediency, accessibility, and cost-effectiveness of ancillary testing during pathologic examination and reporting. OBJECTIVE.­: To provide a practical approach to handling pediatric soft tissue tumor specimens, including volume considerations, immunohistochemical staining panel recommendations, genetic and molecular testing approaches, and other processes that impact the quality and efficiency of tumor tissue triage. DATA SOURCES.­: The World Health Organization Classification of Soft Tissue and Bone Tumors, 5th edition, other recent literature investigating tissue handling, and the collective clinical experience of the group are used in this manuscript. CONCLUSIONS.­: Pediatric soft tissue tumors can be difficult to diagnose, and evaluation can be improved by adopting a thoughtful, algorithmic approach to maximize available tissue and minimize time to diagnosis.

ALK rearrangements in infantile fibrosarcoma-like spindle cell tumours of soft tissue and kidney.

AIMS: Recurrent alterations in receptor tyrosine kinase (RTK) and downstream effectors are described in infantile fibrosarcoma (IFS)/cellular congenital mesoblastic nephroma (cCMN) and a subset of spindle cell sarcomas, provisionally designated 'NTRK-rearranged' spindle cell neoplasms. These two groups of tumours demonstrate overlapping morphologies and harbour alterations in NTRK1/2/3, RET, MET, ABL1, ROS1, RAF1 and BRAF, although their relationship is not fully elucidated. We describe herein a cohort of paediatric tumours with clinicopathological features not typical for inflammatory myofibroblastic tumour, but rather with similarities to cCMN/IFS harbouring ALK fusions. METHODS AND RESULTS: Clinicopathological features were assessed and partner agnostic targeted RNA sequencing on clinically validated platforms were performed. Tumours occurred in patients aged from 2 to 10 years (median age 2 years) with a 2:2 male to female ratio and an average size of 8.4 cm. Two tumours arose in soft tissues and two in the kidney. Morphological features included spindle to ovoid cells arranged in long fascicles or haphazardly within a myxoid to collagenised stroma; a subset of cases had either dilated, ectatic vessels or focal perivascular hyalinosis. By immunohistochemistry, all cases tested showed cytoplasmic expression of anaplastic lymphoma kinase (ALK) and one case demonstrated co-expression of CD34 and S100. CONCLUSIONS: This series of ALK-rearranged IFS-like tumours expands the spectrum of targetable kinases altered in these tumours and reinforces the potential overlap between IFS/cCMN-like tumours and the provisional entity of 'NTRK-rearranged' spindle cell neoplasms.

Local Control For High-Grade Nonrhabdomyosarcoma Soft Tissue Sarcoma Assigned to Radiation Therapy on ARST0332: A Report From the Childrens Oncology Group.

PURPOSE: The ARST0332 trial for pediatric and young adults with nonrhabdomyosarcoma soft tissue sarcoma (NRSTS) used risk-based treatment including primary resection with lower-than-standard radiation doses to optimize local control (LC) while minimizing long-term toxicity in those requiring radiation therapy (RT). RT for high-grade NRSTS was based on extent of resection (R0: negative margins, R1: microscopic margins, R2/U: gross disease/unresectable); those with >5 cm tumors received chemotherapy (CT; ifosfamide/doxorubicin). This analysis evaluates LC for patients assigned to RT and prognostic factors associated with local recurrence (LR). METHODS AND MATERIALS: Patients aged <30 years with high-grade NRSTS received RT (55.8 Gy) for R1 ≤5 cm tumor (arm B); RT (55.8 Gy)/CT for R0/R1 >5 cm tumor (arm C); or neoadjuvant RT (45 Gy)/CT plus delayed surgery, CT, and postoperative boost to 10.8 Gy R0 <5 mm margins/R1 or 19.8 Gy for R2/unresected tumors (arm D). RESULTS: One hundred ninety-three eligible patients had 24 LRs (arm B 1/15 [6.7%], arm C 7/65 [10.8%], arm D 16/113 [14.2%]) at median time to LR of 1.1 years (range, 0.11-5.27). Of 95 eligible for delayed surgery after neoadjuvant therapy, 89 (93.7%) achieved R0/R1 margins. Overall LC after RT were as follows: R0, 106 of 109 (97%); R1, 51 of 60 (85%); and R2/unresectable, 2 of 6 (33%). LR predictors include extent of delayed resection (P <.001), imaging response before delayed surgery (P < .001), histologic subtype (P <.001), and no RT (P = .046). The 5-year event-free survival was significantly lower (P = .0003) for patients unable to undergo R0/R1 resection. CONCLUSIONS: Risk-based treatment for young patients with high-grade NRSTS treated on ARST0332 produced very high LC, particularly after R0 resection (97%), despite lower-than-standard RT doses. Neoadjuvant CT/RT enabled delayed R0/R1 resection in most patients and is preferred over adjuvant therapy due to the lower RT dose delivered.

A risk-based treatment strategy for non-rhabdomyosarcoma soft-tissue sarcomas in patients younger than 30 years (ARST0332): a Children's Oncology Group prospective study.

BACKGROUND: Tumour grade, tumour size, resection potential, and extent of disease affect outcome in paediatric non-rhabdomyosarcoma soft-tissue sarcoma (NRSTS), but no risk stratification systems exist and the standard of care is poorly defined. We developed a risk stratification system from known prognostic factors and assessed it in the context of risk-adapted therapy for young patients with NRSTS. METHODS: In this prospective study, eligible patients enrolled in 159 hospitals in three countries were younger than 30 years, had a Lansky (patients ≤16 years) or Karnofsky (patients >16 years) performance status score of at least 50, and a new diagnosis of a WHO (2002 criteria) intermediate (rarely metastasising) or malignant soft-tissue tumour (apart from tumour types eligible for other Children's Oncology Group studies and tumours for which the therapy in this trial was deemed inappropriate), malignant peripheral nerve sheath tumour, non-metastatic and grossly resected dermatofibrosarcoma protuberans, undifferentiated embryonal sarcoma of the liver, or unclassified malignant soft-tissue sarcoma. Each patient was assigned to one of three risk groups and one of four treatment groups. Risk groups were: low (non-metastatic R0 or R1 low-grade, or ≤5 cm R1 high-grade tumour); intermediate (non-metastatic R0 or R1 >5 cm high-grade, or unresected tumour of any size or grade); or high (metastatic tumour). The treatment groups were surgery alone, radiotherapy (55·8 Gy), chemoradiotherapy (chemotherapy and 55·8 Gy radiotherapy), and neoadjuvant chemoradiotherapy (chemotherapy and 45 Gy radiotherapy, then surgery and radiotherapy boost based on margins with continued chemotherapy). Chemotherapy included six cycles of ifosfamide 3 g/m2 per dose intravenously on days 1-3 and five cycles of doxorubicin 37·5 mg/m2 per dose intravenously on days 1-2 every 3 weeks with sequence adjusted on the basis of timing of surgery or radiotherapy. The primary outcomes were event-free survival, overall survival, and the pattern of treatment failure. Analysis was done per protocol. This study has been completed and is registered with ClinicalTrials.gov, NCT00346164. FINDINGS: Between Feb 5, 2007, and Feb 10, 2012, 550 eligible patients were enrolled, of whom 21 were treated in the incorrect group and excluded from this analysis. 529 evaluable patients were included in the analysis: low-risk (n=222), intermediate-risk (n=227), high-risk (n=80); surgery alone (n=205), radiotherapy (n=17), chemoradiotherapy (n=111), and neoadjuvant chemoradiotherapy (n=196). At a median follow-up of 6·5 years (IQR 4·9-7·9), 5-year event-free survival and overall survival were: 88·9% (95% CI 84·0-93·8) and 96·2% (93·2-99·2) in the low-risk group; 65·0% (58·2-71·8) and 79·2% (73·4-85·0) in the intermediate-risk group; and 21·2% (11·4-31·1) and 35·5% (23·6-47·4) in the high-risk group, respectively. Risk group predicted event-free survival and overall survival (p<0·0001). No deaths from toxic events during treatment were reported. Nine patients had unexpected grade 4 adverse events (chemoradiotherapy group, n=2; neoadjuvant chemoradiotherapy group, n=7), including three wound complications that required surgery (all in the neoadjuvant chemoradiotherapy group). INTERPRETATION: Pre-treatment clinical features can be used to effectively define treatment failure risk and to stratify young patients with NRSTS for risk-adapted therapy. Most low-risk patients can be cured without adjuvant therapy, thereby avoiding known long-term treatment complications. Survival remains suboptimal for intermediate-risk and high-risk patients and novel therapies are needed. FUNDING: National Institutes of Health, St Baldrick's Foundation, Seattle Children's Foundation, American Lebanese Syrian Associated Charities.

Magnetic resonance and computed tomography imaging features of epithelioid sarcoma in children and young adults with pathological and clinical correlation: a report from Children's Oncology Group study ARST0332.

OBJECTIVE: To correlate imaging features of epithelioid sarcoma in children and young adults enrolled in Children's Oncology Group study ARST0332 with clinical and pathological findings. MATERIALS AND METHODS: Fifteen patients (6 males; median age 16.1 years, range 6.5-24.8 years) with epithelioid sarcoma enrolled in ARST0332 had preoperative imaging (MRI, n=10; CT, n=5) that was reviewed by two radiologists who recorded numerous features including presence and percentage of tumor necrosis, presence of surrounding edema, and lymph node involvement. Discrepancies between reviewers were adjudicated by concurrent re-review. We correlated imaging findings with histological assessment of percentage tumor necrosis, proximal- vs. classic-type histology, lymph node involvement and recurrence. RESULTS: Eleven patients (11/15, 73%) had proximal-type histology tumors. Ten of 14 tumors (71%) had imaging evidence of necrosis. Among the nine tumors with imaging and histological estimates of percentage necrosis, agreement was within 30% (in six tumors there was ≤10% difference between pathology and imaging). All 10 tumors imaged with MRI had surrounding edema. Four patients had biopsy-proven nodal involvement; all had necrotic nodes on imaging. There were four false-positives for nodal involvment by imaging. Twelve patients (12/15, 80%) had recurrences (local only, n=1; local and distant, n=1; distant only, n=10). CONCLUSION: Proximal-type histology was prevalent in this young cohort with preoperative imaging. Necrosis is common in primary tumors and involved nodes. There is good agreement between histological and imaging estimates of primary tumor necrosis. Surrounding tumor edema is common in this tumor, which is known to spread along fascial planes.

Undifferentiated Sarcomas in Children Harbor Clinically Relevant Oncogenic Fusions and Gene Copy-Number Alterations: A Report from the Children's Oncology Group.

Purpose: A comprehensive analysis of the genomics of undifferentiated sarcomas (UDS) is lacking. We analyzed copy-number alterations and fusion status in patients with UDS prospectively treated on Children's Oncology Group protocol ARST0332.Experimental Design: Copy-number alterations were assessed by OncoScan FFPE Express on 32 UDS. Whole-exome and transcriptome libraries from eight tumors with sufficient archived material were sequenced on HiSeq (2 × 100 bp). Targeted RNA-sequencing using Archer chemistry was performed on two additional cases.Results: Five-year overall survival for patients with UDS was 83% (95% CI, 69%-97%) with risk-adapted therapy (surgery, chemotherapy, and radiotherapy). Both focal and arm-level copy-number alterations were common including gain of 1q (8/32, 25%) and loss of 1p (7/32, 22%), both of which occurred more often in clinically defined high-risk tumors. Tumors with both loss of 1p and gain of 1q carried an especially poor prognosis with a 5-year event-free survival of 20%. GISTIC analysis identified recurrent amplification of FGF1 on 5q31.3 (q = 0.03) and loss of CDKN2A and CDKN2B on 9p21.3 (q = 0.07). Known oncogenic fusions were identified in eight of 10 cases analyzed by next-generation sequencing.Conclusions: Pediatric UDS generally has a good outcome with risk-adapted therapy. A high-risk subset of patients whose tumors have copy-number loss of 1p and gain of 1q was identified with only 20% survival. Oncogenic fusions are common in UDS, and next-generation sequencing should be considered for children with UDS to refine the diagnosis and identify potentially targetable drivers. Clin Cancer Res; 24(16); 3888-97. ©2018 AACR.

Opportunities for Improvement in Pathology Reporting of Childhood Nonrhabdomyosarcoma Soft Tissue Sarcomas: A Report From Children's Oncology Group (COG) Study ARST0332.

OBJECTIVES: Treatment of soft tissue tumors in young patients relies on the diagnostic information conveyed in the pathology report. We examined pathology reports from Children's Oncology Group ARST0332 for inclusion of data elements required in published guidelines. METHODS: Pathology reports for 551 eligible patients were examined for required data elements defined by the College of American Pathologists, including tissue type, procedure, tumor site, tumor maximum diameter, macroscopic extent of tumor, histologic type, mitotic rate, extent of necrosis, tumor grade, margin status, use of ancillary studies, and pathologic stage. RESULTS: Only 65 (12%) of 551 reports included all required data elements. Of reports containing synoptic templates, 57% were complete. CONCLUSIONS: This study reveals significant opportunity to improve the quality of pathology reports in young patients with soft tissue tumors. Use of templates or checklists improves completeness of reports.

The Evolution of Pediatric Soft Tissue Sarcoma Classification in the Last 50 Years.

This review discusses the history of the classification of soft tissue sarcomas in children and adolescents, the current transition toward integration of morphology and molecular genetics as new entities emerge, and future perspectives.

Radiation-induced Sarcomas Occurring in Desmoid-type Fibromatosis Are Not Always Derived From the Primary Tumor.

Desmoid-type fibromatosis is a rare, highly infiltrative, locally destructive neoplasm that does not metastasize, but recurs often after primary surgery. Activation of the Wnt/ß-catenin pathway is the pathogenic mechanism, caused by an activating mutation in exon 3 of CTNNB1 (85% of the sporadic patients). Radiotherapy is a frequent treatment modality with a local control rate of approximately 80%. In very rare cases, this may result in the development of radiation-induced sarcoma. It is unclear whether these sarcomas develop from the primary tumor or arise de novo in normal tissue. In 4 tertiary referral centers for sarcoma, 6 cases of desmoid-type fibromatosis that subsequently developed sarcoma after radiotherapy were collected. The DNA sequence of CTNNB1 exon 3 in the desmoid-type fibromatosis and the subsequent postradiation sarcoma was determined. Sarcomas developed 5 to 21 years after the diagnosis of desmoid-type fibromatosis and included 2 osteosarcomas, 2 high-grade undifferentiated pleomorphic sarcomas, 1 fibrosarcoma, and 1 undifferentiated spindle cell sarcoma. Three patients showed a CTNNB1 hotspot mutation (T41A, S45F, or S45N) in both the desmoid-type fibromatosis and the radiation-induced sarcoma. The other 3 patients showed a CTNNB1 mutation in the original desmoid-type fibromatosis (2 with a T41A and 1 with an S45F mutation), which was absent in the sarcoma. In conclusion, postradiation sarcomas that occur in the treatment area of desmoid-type fibromatosis are extremely rare and can arise through malignant transformation of CTNNB1-mutated desmoid fibromatosis cells, but may also originate from CTNNB1 wild-type normal cells lying in the radiation field.

MRI and CT of Low-Grade Fibromyxoid Sarcoma in Children: A Report From Children's Oncology Group Study ARST0332.

OBJECTIVE: The purpose of this article is to determine the MRI and CT features of low-grade fibromyxoid sarcoma in children. MATERIALS AND METHODS: We retrospectively analyzed images of 11 pediatric patients with low-grade fibromyxoid sarcoma from a phase 3 clinical trial of nonrhabdomyosarcoma soft-tissue sarcoma (Children's Oncology Group Protocol ARST0332). MRI and CT were performed in 10 and four patients, respectively. Location, size, margin, and composition on imaging were correlated with pathologic findings. RESULTS: Tumors were located in the extremities in nine patients, and one tumor each was located in the tongue and lung. Tumors were deep in seven patients and superficial in four patients. All tumors were well defined, solitary, and nonmetastatic at presentation. Tumors were complex solid-cystic in eight patients and completely solid in three patients. On T1-weighted images, all tumors had at least some areas hypointense to muscles, and six had a split-fat sign. On STIR or T2-weighted images, eight tumors had areas hypointense to adjacent muscle, and eight tumors had fluid signal intensity. On contrast-enhanced MRI studies, eight tumors had thick enhancing internal septations, and three had peripheral nodular gyriform enhancement. When we correlated imaging to pathologic findings, areas with hypointense signal intensity on both T1- and T2-weighted images were likely related to fibrous component; areas with fluid signal intensity on T2-weighted images were likely related to myxoid component. On CT, all four tumors were hypodense to muscle, and one tumor showed punctate calcific foci. CONCLUSION: Low-grade fibromyxoid sarcoma is hypodense to muscle on CT. MRI may identify both fibrous and myxoid components of this rare pediatric soft-tissue sarcoma.

Imaging features of alveolar soft-part sarcoma: a report from Children's Oncology Group Study ARST0332.

OBJECTIVE: There are few studies in the literature regarding the imaging features of alveolar soft-part sarcoma (ASPS). We performed a comprehensive assessment of the imaging characteristics of this rare tumor to determine whether there are features that suggest the diagnosis. MATERIALS AND METHODS: Twenty-two subjects with ASPS underwent pretherapy imaging as part of enrollment in Children's Oncology Group protocol ARST0332 for the treatment of nonrhabdomyosarcoma soft-tissue sarcomas: 16 patients underwent MRI; three, CT; and three, both MRI and CT. Two radiologists retrospectively reviewed the imaging studies by consensus and recorded tumor location, size, contour, internal architecture, signal characteristics, presence of flow voids, and enhancement patterns. RESULTS: The 12 females and 10 males in the study group ranged in age from 8 to 23 years 7 months (mean, 15 years 8 months). The most common anatomic site was the lower extremity (12/22, 55%) followed by the upper extremity (4/22, 18%). The maximal tumor diameter ranged from 2.3 to 20.0 cm (median, 5.9 cm). All tumors imaged with MRI had flow voids (19/19, 100%), and 19 (19/22, 86%) had large peripheral vessels, lobulated margins, and nodular internal architecture. Unenhanced T1-weighted MRI was available for 18 tumors: 14 (14/18, 78%) appeared slightly hyperintense to muscle. Of the 16 tumors imaged with contrast material, 11 (11/16, 69%) showed intense enhancement and five (5/16, 31%), moderate enhancement. Six tumors (6/16, 38%) had a thick enhancing peripheral rim with a nonenhancing center consistent with necrosis. CONCLUSION: The imaging features of ASPS include flow voids, large peripheral vessels, internal nodularity, and lobulated margins. Contrast administration produces intense to moderate enhancement, sometimes with a thick enhancing peripheral rim around central necrosis. Extremity tumors with these imaging features in a child or young adult should suggest the diagnosis of ASPS.

Desmoid-type fibromatosis-associated Gardner fibromas: prevalence and impact on local recurrence.

Although Gardner fibroma is a precursor lesion of desmoid tumor, the prevalence and prognostic importance of Gardner fibroma associated with desmoid tumors has not been systematically studied in adults. From 129 patients with desmoid-type fibromatosis, 170 specimens were re-examined for the presence of an associated Gardner fibroma. Clinicopathologic features of Gardner fibroma-associated desmoid-type fibromatosis were compared to desmoid tumors without associated Gardner fibroma. Recurrence-free survival was compared using multivariate Cox proportional hazard regression to account for known confounding factors. Of 104 evaluable primary desmoid tumor resections, 25 (24%) had an associated Gardner fibroma. When previous incisional biopsies and resection specimens of locally recurrent desmoid tumors were also examined, the overall prevalence of associated Gardner fibroma was 37%. Desmoid tumors arising in high risk anatomic sites (extremities or deep soft tissues of the back and chest wall) were more often associated with Gardner fibroma than tumors at other sites. Median recurrence-free survival for patients with Gardner fibroma-associated desmoid-type fibromatosis was 3.2 years, whereas median survival for patients without associated Gardner fibroma was >25 years (hazard ratio 2.8; P = 0.001). Although the presence of Gardner fibroma had no impact on the recurrence rate of desmoid tumors arising at high risk anatomic sites, associated Gardner fibroma increased the risk of recurrence 4-fold for desmoid tumors at low risk anatomic sites. Associated Gardner fibroma is under-recognized in desmoid-type fibromatosis and increases the risk of local recurrence for a subgroup of patients.

Inflammatory myofibroblastic tumors harbor multiple potentially actionable kinase fusions.

UNLABELLED: Inflammatory myofibroblastic tumor (IMT) is a neoplasm that typically occurs in children. The genetic landscape of this tumor is incompletely understood and therapeutic options are limited. Although 50% of IMTs harbor anaplastic lymphoma kinase (ALK) rearrangements, no therapeutic targets have been identified in ALK-negative tumors. We report for the first time that IMTs harbor other actionable targets, including ROS1 and PDGFRß fusions. We detail the case of an 8-year-old boy with treatment-refractory ALK-negative IMT. Molecular tumor profiling revealed a ROS1 fusion, and he had a dramatic response to the ROS1 inhibitor crizotinib. This case prompted assessment of a larger series of IMTs. Next-generation sequencing revealed that 85% of cases evaluated harbored kinase fusions involving ALK, ROS1, or PDGFRß. Our study represents the most comprehensive genetic analysis of IMTs to date and also provides a rationale for routine molecular profiling of these tumors to detect therapeutically actionable kinase fusions. SIGNIFICANCE: Our study describes the most comprehensive genomics-based evaluation of IMT to date. Because there is no "standard-of-care" therapy for IMT, the identification of actionable genomic alterations, in addition to ALK, is expected to redefine management strategies for patients with this disease.

Alveolar soft part sarcoma and granular cell tumor: an immunohistochemical comparison study.

Although the histologic features of alveolar soft part sarcoma and granular cell tumor are typically distinctive, occasional cases show a significant morphologic overlap. Differentiating these entities is crucial because granular cell tumor is almost always benign and alveolar soft part sarcoma is invariably malignant. We evaluated a panel of immunohistochemical stains (S-100 protein, inhibin, SOX10, nestin, calretinin, and TFE3) in 13 alveolar soft part sarcomas and 11 granular cell tumors. Tissue sections were also stained by the periodic acid-Schiff method after diastase digestion (PAS-D) and evaluated for coarse cytoplasmic granularity or crystalline cytoplasmic inclusions. S-100 protein, inhibin, SOX10, and nestin each distinguished granular cell tumor and alveolar soft part sarcoma with 100% sensitivity and specificity. PAS-D staining also distinguished cases with 100% accuracy, as granular cell tumor consistently demonstrated coarsely granular, PAS-D-positive cytoplasm and alveolar soft part sarcoma showed only focal intracytoplasmic crystalline inclusions. Although all granular cell tumors were calretinin positive, so were 46% of alveolar soft part sarcomas. TFE3 was positive in 91% of granular cell tumors and all alveolar soft part sarcomas. Together with PAS-D, immunohistochemical stains for S-100 protein, inhibin, SOX10, and nestin accurately identify alveolar soft part sarcoma and granular cell tumor. Although TFE3 has been reported as a relatively specific marker for alveolar soft part sarcoma, it should be recalled that it is also expressed in most granular cell tumors.

Fibrous hamartoma of infancy: a clinicopathologic analysis of 60 cases.

Fibrous hamartoma of infancy is a benign soft tissue tumor with a characteristic triphasic organoid histologic appearance. It typically occurs within the first 2 years of life. The usual anatomic locations include the upper extremities, axilla, and upper back. Diagnostic challenges occur when this tumor arises in older children, outside of the usual anatomic sites, or when unusual histologic features are encountered. This study reports 60 cases of fibrous hamartoma of infancy from institutional and consultation files. All had a triphasic organoid histologic pattern, but half also displayed an unusual pseudoangiomatous histologic pattern. The male to female ratio was 2.0 (40 boys, 20 girls), with a mean age of 1.5 years (range, 16 d to 8 y) at diagnosis. Tumor size ranged from 0.5 to 9 cm, with a mean of 3.7 cm. Sites included the trunk (40 cases), extremities (17 cases), and head and neck (3 cases). All cases had triphasic elements of mature fibrous tissue, mature adipose tissue, and immature mesenchymal tissue in varying proportions, with the additional pseudoangiomatous pattern in 32 cases. Immunohistochemical analysis demonstrated reactivity for smooth muscle actin and CD34 in the mature fibrous tissue, S100 protein in the mature adipose tissue, and variable CD34 reactivity in immature mesenchymal and pseudoangiomatous foci. Ki-67 proliferative activity was noted in the immature mesenchymal and pseudoangiomatous foci, and Bcl-2 reactivity was restricted to mesenchymal and pseudoangiomatous foci. Follow-up information in 12 cases revealed no evidence of recurrence in 10 patients and local recurrence in 2 patients, each at 3.5 years after primary excision. This study demonstrates an expanded age range (up to 8 y) and anatomic distribution (30 cases outside of the classic locations of the upper extremities, axilla, and upper back) of fibrous hamartoma of infancy. The pseudoangiomatous morphologic variation can lead to challenges in diagnosis and may reflect a maturational phenomenon from the immature mesenchymal component.

Plexiform fibromyxoma: report of two pediatric cases and review of the literature.

Plexiform fibromyxoma is a distinctive mesenchymal neoplasm usually arising in the gastric antrum. We report 2 cases of this entity in pediatric patients, including the first case arising in the esophagus. The patients were a 16-year-old female who presented with chest pain and was found on computed tomographic scan to have a midesophageal mass at the level of the carina, and an 11-year-old female with a gastric mass. Both patients underwent surgical resection of their tumors, which histologically exhibited a plexiform growth pattern with multiple nodules in the muscularis propria and infiltrative borders. The nodules were composed of a rich myxoid stroma with bland uniform spindle cells, no mitoses or necrosis, and delicate blood vessels in the background. Immunohistochemical studies demonstrated that the tumor cells were immunoreactive with smooth muscle actin and not reactive with S-100, CD34, desmin, and c-kit (CD117). We report the first case of plexiform fibromyxoma originating in the esophagus, emphasize its occurrence in pediatric patients, and review the related literature.

Syndrome-associated soft tissue tumours.

Soft tissue neoplasms may be associated with a variety of genetic disorders and malformation syndromes, especially when they arise in children, adolescents and early adulthood. This review summarizes the principal histopathological types of soft tissue tumours which occur in various syndromes, with an emphasis on pathological features, genetic aspects and considerations for the diagnostic pathologist.