PRAME Expression Is a Useful Tool in the Diagnosis of Primary and Metastatic Dedifferentiated and Undifferentiated Melanoma.

Although mostly recognized in the metastatic setting dedifferentiated and undifferentiated melanomas are increasingly recognized as cutaneous and, less commonly, mucosal primary tumors. Their diagnosis is challenging and dependent on sampling and recognition of a conventional melanoma precursor and/or detection of a mutation in a conventional melanoma driver gene. PRAME immunohistochemistry has recently become an important ancillary tool in the separation of melanoma from benign nevi, but no comprehensive studies exist regarding its value in the detection of dedifferentiated and undifferentiated melanomas and their separation from atypical fibroxanthoma and pleomorphic dermal sarcoma, the main differential diagnoses on sun-damaged skin. After retrieval from archival files, we performed PRAME immunohistochemistry on 11 primary and 10 metastatic dedifferentiated and undifferentiated melanomas, 11 atypical fibroxanthomas, and 10 pleomorphic dermal sarcomas. Nuclear staining was assigned extent (ranging from 0 to 4 and reflecting the percentage of PRAME-positive tumor nuclei) and intensity scores (graded as absent, weak, moderate, and strong, with assigned scores ranging from 0 to 3) with combined scores ranging from 0 to 7. Both primary and metastatic dedifferentiated and undifferentiated melanomas showed strong and diffuse nuclear PRAME staining with median combined scores of 7. Strong and diffuse staining was also seen in all conventional melanoma precursors except for desmoplastic melanoma. In contrast, PRAME staining in atypical fibroxanthoma and pleomorphic dermal sarcoma was patchy and weak with median combined scores of 2. Our data emphasize the diagnostic utility of PRAME staining as a first screening tool in the detection and workup of dedifferentiated and undifferentiated melanomas, both in the primary and metastatic settings. PRAME immunohistochemistry is particularly helpful as it is also positive in tumors without a recognizable conventional melanoma precursor and in those associated with desmoplastic melanomas, where PRAME is typically found to be negative.

UV-radiation and MC1R germline mutations are risk factors for the development of conventional and spitzoid melanomas in children and adolescents.

BACKGROUND: Genomic characterisation has led to an improved understanding of adult melanoma. However, the aetiology of melanoma in children is still unclear and identifying the correct diagnosis and therapeutic strategies remains challenging. METHODS: Exome sequencing of matched tumour-normal pairs from 26 paediatric patients was performed to study the mutational spectrum of melanomas. The cohort was grouped into different categories: spitzoid melanoma (SM), conventional melanoma (CM), and other melanomas (OT). FINDINGS: In all patients with CM (n = 10) germline variants associated with melanoma were found in low to moderate melanoma risk genes: in 8 patients MC1R variants, in 2 patients variants in MITF, PTEN and BRCA2. Somatic BRAF mutations were detected in 60% of CMs, homozygous deletions of CDKN2A in 20%, TERTp mutations in 30%. In the SM group (n = 12), 5 patients carried at least one MC1R variant; somatic BRAF mutations were detected in 8.3%, fusions in 25% of the cases. No SM showed a homozygous CDKN2A deletion nor a TERTp mutation. In 81.8% of the CM/SM cases the UV damage signatures SBS7 and/or DBS1 were detected. The patient with melanoma arising in giant congenital nevus (CNM) demonstrated the characteristic NRAS Q61K mutation. INTERPRETATION: UV-radiation and MC1R germline variants are risk factors in the development of conventional and spitzoid paediatric melanomas. Paediatric CMs share genomic similarities with adult CMs while the SMs differ genetically from the CM group. Consistent genetic characterization of all paediatric melanomas will potentially lead to better subtype differentiation, treatment, and prevention in the future. FUNDING: Found in Acknowledgement.

[Multiple, eruptive epithelioid hemangiomas of the scalp]. / Multiple, eruptive epitheloide Hämangiome der Kopfhaut.

Epithelioid hemangioma is a benign vascular neoplasm with a characteristic histological and immunohistochemical pattern, characterized by a lymphocytic inflammatory infiltrate with admixed eosinophils and FOS­B expression. The correct diagnosis is of particular relevance, since malignant vascular tumors with differentiated epithelioid cells can also be considered in the differential diagnosis. We present a patient with multiple epithelioid hemangiomas of the scalp accompanied by severe pain and itching. The long history of multiple therapeutic attempts illustrates the limited success of currently available treatment options.

S1-guideline cutaneous and subcutaneous leiomyosarcoma.

Superficial leiomyosarcomas (LMS) are rare skin cancers (2-3% of cutaneous sarcomas) that originate from dermally located hair follicle muscles, dartos or areolar muscles (cutaneous/dermal LMS), or from vascular muscle cells of the subcutaneous adipose tissue (subcutaneous LMS). These superficial LMS are distinct from LMS of the deep soft tissues. Leiomyosarcomas are typically localized at the lower extremities, trunk or capillitium, and present as painful, erythematous to brownish nodules. Diagnosis is made by histopathology. The treatment of choice for primary LMS is complete (R0) microscopically controlled excision, with safety margins of 1 cm in dermal LMS, and 2 cm in subcutaneous LMS, if possible. Non-resectable or metastatic LMS require individual treatment decisions. After R0 resection with 1 cm safety margins, the local recurrence rate of dermal LMS is very low, and metastasis is very rare. Subcutaneous LMS, very large, or incompletely excised LMS recur and metastasize more frequently. For this reason, clinical follow-up examinations are recommended every six months for cutaneous LMS, and every three months for subcutaneous LMS within the first two years (in subcutaneous LMS including locoregional lymph node sonography). Imaging such as CT/MRI is indicated only in primary tumors with special features, recurrences, or already metastasized tumors.

Undifferentiated pleomorphic sarcoma of the breast with neoplastic fever: case report and genomic characterization.

PURPOSE: Primary breast sarcomas are extraordinary rare, in particular undifferentiated pleomorphic sarcoma (UPS). UPS with neoplastic fever (UPS-NF) of the breast has not been reported yet. Here, we present an extended UPS-NF of the breast including its comprehensive molecular workup. METHODS: A 58-year-old female presented with general malaise, fever spikes, weight loss, and a massively swollen left breast. C-reactive protein and blood leucocytes were significantly increased. However, repeated blood cultures and smears were all sterile. Histopathology of the abscess-forming tumor revealed an undifferentiated malignancy with numerous of tumor giant cells as well as spindle-shaped cells with nuclear pleomorphism and hyperchromasia. Immunohistochemistry demonstrated partial, patchy desmin staining and weak heterogonous neuron-specific enolase immunoreactivity of tumor cells, but a focal staining for Melan-A. RESULTS: Neither common melanoma driver mutations nor an ultraviolet mutational signature was detected by whole genome sequencing. Using FISH and RT-PCR we also excluded translocations characteristic for clear cell sarcoma. Thus, the diagnosis of inflammatory UPS-NF of the breast was considered highly probable. Despite a complete mastectomy, the tumor recurred after only three months. This recurrence was treated with a combination of ipilimumab and nivolumab based on the primary tumor's TPS score for PD-L1 of 30%. After an initial response, however, the tumor was progressive again. CONCLUSION: We describe here the first case of UPS-NF of the breast, which shows great clinical and histopathologic resemblances to previously reported UPS-NF of other anatomic localizations.

Dermal lipofibromatosis-like neural tumor.

BACKGROUND: Lipofibromatosis-like neural tumor (LPF-NT) is a rare soft tissue typically occurring in the subcutis, characterized by a cellular proliferation of CD34- and S100-protein positive spindle-shaped tumor cells with an infiltrative growth pattern. OBJECTIVE: To describe five cases arising mainly in the dermis in order to expand their morphologic spectrum. METHODS: H&E slides were reviewed, and all cases were stained for CD34, SOX10, S100, ALK, and NTRK1 and some of them with additional staining. RESULTS: Patients were three males and two females with a mean age of 44.8 years (14-68 years). Histopathologically, all cases were characterized by a dense dermal infiltration by monomorphous, mildly atypical, plump to spindle-shaped tumor cells, staining diffusely positive for CD34, S100, and NTRK1 but were negative for S100, EMA, NKIC3, MNF116, SMA, ALK, and desmin. LIMITATIONS: Limited clinical information. CONCLUSION: LPL-NT can be located mainly in the dermis. Sixty percent of our cases showed typical areas of LPL-NT intermingled with more plump cells like the ones in fibrous hamartoma of infancy. We recommend a panel of CD34, S100, and NTRK1 antibodies not only in subcutaneous spindle cell neoplasms but also in the ones predominantly involving the dermis in order to make an accurate diagnosis.

S1-guideline atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS).

Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare cutaneous neoplasms representing histomorphological, genetic as well as epigenetic variants of a disease spectrum. Both tumors typically manifest as nonspecific, often ulcerated, skin- to flesh-colored nodules in chronically sun-damaged skin of elderly male patients. AFX is a rather well demarcated, often rapidly growing tumor. PDS tumors are poorly circumscribed and are characterized by aggressive infiltrative growth. Fast as well as slow growth behavior has been reported for both tumors. Histologically, both are composed of spindle-shaped and epithelioid tumor cells with pleomorphic nuclei as well as atypical multinucleated giant cells. Atypical mitoses are common. In contrast to AFX, PDS involves relevant parts of the subcutis and shows areas of tumor necrosis and/or perineural infiltration. Due to the poorly differentiated nature of AFX/PDS (Grade 3), histopathologically similar cutaneous sarcomas, undifferentiated carcinomas, melanomas and other diseases have to be excluded by immunohistochemical analysis. The treatment of choice is micrographically controlled surgery. In cases of AFX, a cure can be assumed after complete excision. Local recurrence rates are low as long as PDS tumors are surgically removed with a safety margin of 2 cm. Metastasis is rare and mostly associated with very thick or incompletely excised tumors; it mainly affects the skin and lymph nodes. Distant metastasis is even more rare. No approved and effective systemic therapy has been established.

Spindle Cell Sarcoma of the Uterine Corpus With Adipose Metaplasia: Expanding the Morphologic Spectrum of Neoplasms With MEIS1-NCOA2 Gene Fusion.

We report a spindle cell sarcoma arising in the uterine corpus of a 26-yr-old patient. The patient underwent a simple hysterectomy and the uterine corpus contained a 9 cm tumor showing nodular and "finger-like" myometrial invasion. Histologically, the tumor was composed of a monomorphic population of atypical spindle cells which contained widespread foci of cytologically benign adipocytes. Immunohistochemistry revealed diffuse strong positivity for CD10, CD56, and CD99 and diffuse weak positive staining with ER and WT1 while smooth muscle markers, S100, TLE1, and cyclin D1 were negative. Total RNA sequencing identified an in-frame fusion between exon 6 of MEIS1 and exon 12 of NCOA2. Copy number analysis revealed few aberrations with no deletions or amplifications identified. No adjuvant therapy was given and the patient is disease-free 9 yr after initial diagnosis. This case represents the second report of a uterine sarcoma harboring a MEIS1-NCOA2/1 gene fusion and expands the morphologic spectrum of recently reported spindle cell sarcomas arising in the genitourinary tract harboring MEIS1-NCOA2/1 gene fusions. This is the first reported case of such tumors with an adipocytic component.

The contribution of Juan Rosai to the pathology of soft tissue tumors.

The conceptual evolution in the field of soft tissue tumor pathology has been mostly driven by a relatively small group of individuals that includes giants of the past and the present such as James Ewing, Raffaele Lattes, Arthur Purdy Stout, Franz Enzinger, Sharon Weiss, Lennart Angervall, Harry Evans, Marku Miettinen, and Christopher Fletcher. Juan Rosai, not only exerted an immense impact on surgical pathology in general, but in consideration of his unique talent in identifying novel clinicopathologic entities, has also contributed remarkably to current understanding of mesenchymal neoplasms. The creation of desmoplastic small round cell tumor certainly ranks among his most relevant efforts, although he actually put his mark on a broad variety of soft tissue lesions, including vascular neoplasms. It would be impossible to include in a single article all the entities that he created or contributed to refine; therefore, this review is limited to a selection of what we believe represent true milestones.

Intimal sarcomas and undifferentiated cardiac sarcomas carry mutually exclusive MDM2, MDM4, and CDK6 amplifications and share a common DNA methylation signature.

Undifferentiated mesenchymal tumors arising from the inner lining (intima) of large arteries are classified as intimal sarcomas (ISA) with MDM2 amplification as their molecular hallmark. Interestingly, undifferentiated pleomorphic sarcomas (UPS) of the heart have recently been suggested to represent the cardiac analog of ISA due to morphological overlap and high prevalence of MDM2 amplifications in both neoplasms. However, little is known about ISAs and cardiac UPS without MDM2 amplifications and molecular data supporting their common classification is sparse. Here, we report a series of 35 cases comprising 25 ISAs of the pulmonary artery, one ISA of the renal artery and 9 UPS of the left atrium. Tumors were analyzed utilizing the Illumina Infinium MethylationEPIC BeadChip array, enabling copy number profile generation and unsupervised DNA methylation analysis. DNA methylation patterns were investigated using t-distributed stochastic neighbor embedding (t-SNE) analysis. Histologically, all ISAs and UPS of the left atrium resembled extra-cardiac UPS. All cases exhibited highly complex karyotypes with overlapping patterns between ISA and UPS. 29/35 cases showed mutually exclusive amplifications in the cell-cycle associated oncogenes MDM2 (25/35), MDM4 (2/35), and CDK6 (2/35). We further observed recurrent co-amplifications in PDGFRA (21/35), CDK4 (15/35), TERT (11/35), HDAC9 (9/35), and CCND1 (4/35). Sporadic co-amplifications occurred in MYC, MYCN, and MET (each 1/35). The tumor suppressor CDKN2A/B was frequently deleted (10/35). Interestingly, DNA methylation profiling (t-SNE) revealed an overlap of ISA and cardiac UPS. This "ISA" methylation signature was distinct from potential histologic and molecular mimics. In conclusion, our data reveal MDM4 and CDK6 amplifications in ISAs and UPS of the left atrium, lacking MDM2 amplification. We further report novel co-amplifications of various oncogenes, which may have therapeutic implications. Finally, the genetic and epigenetic concordance of ISAs and UPS of the left atrium further supports a shared pathogenesis and common classification.

The clinicopathologic spectrum and genomic landscape of de-/trans-differentiated melanoma.

Dedifferentiation and transdifferentiation are rare and only poorly understood phenomena in cutaneous melanoma. To study this disease more comprehensively we have retrieved 11 primary cutaneous melanomas from our pathology archives showing biphasic features characterized by a conventional melanoma and additional areas of de-/trans-differentiation as defined by a lack of immunohistochemical expression of all conventional melanocytic markers (S-100 protein, SOX10, Melan-A, and HMB-45). The clinical, histologic, and immunohistochemical findings were recorded and follow-up was obtained. The patients were mostly elderly (median: 81 years; range: 42-86 years) without significant gender predilection, and the sun-exposed skin of the head and neck area was most commonly affected. The tumors were deeply invasive with a mean depth of 7 mm (range: 4-80 mm). The dedifferentiated component showed atypical fibroxanthoma-like features in the majority of cases (7), while additional rhabdomyosarcomatous and epithelial transdifferentiation was noted histologically and/or immunohistochemically in two tumors each. The background conventional melanoma component was of desmoplastic (4), superficial spreading (3), nodular (2), lentigo maligna (1), or spindle cell (1) types. For the seven patients with available follow-up data (median follow-up period of 25 months; range: 8-36 months), two died from their disease, and three developed metastases. Next-generation sequencing of the cohort revealed somatic mutations of established melanoma drivers including mainly NF1 mutations (5) in the conventional component, which was also detected in the corresponding de-/trans-differentiated component. In summary, the diagnosis of primary cutaneous de-/trans-differentiated melanoma is challenging and depends on the morphologic identification of conventional melanoma. Molecular analysis is diagnostically helpful as the mutated gene profile is shared between the conventional and de-/trans-differentiated components. Importantly, de-/trans-differentiation does not appear to confer a more aggressive behavior.

Myxoid pleomorphic liposarcoma-a clinicopathologic, immunohistochemical, molecular genetic and epigenetic study of 12 cases, suggesting a possible relationship with conventional pleomorphic liposarcoma.

Myxoid pleomorphic liposarcoma is a recently defined subtype of liposarcoma, which preferentially involves the mediastinum of young patients and shows mixed histological features of conventional myxoid liposarcoma and pleomorphic liposarcoma. While myxoid pleomorphic liposarcoma is known to lack the EWSR1/FUS-DDIT3 fusions characteristic of the former, additional genetic data are limited. To further understand this tumor type, we extensively examined a series of myxoid pleomorphic liposarcomas by fluorescence in situ hybridization (FISH), shallow whole genome sequencing (sWGS) and genome-wide DNA methylation profiling. The 12 tumors occurred in 6 females and 6 males, ranging from 17 to 58 years of age (mean 33 years, median 35 years), and were located in the mediastinum (n = 5), back, neck, cheek and leg, including thigh. Histologically, all cases consisted of relatively, bland, abundantly myxoid areas with a prominent capillary vasculature, admixed with much more cellular and less myxoid foci containing markedly pleomorphic spindled cells, numerous pleomorphic lipoblasts and elevated mitotic activity. Using sWGS, myxoid pleomorphic liposarcomas were found to have complex chromosomal alterations, including recurrent large chromosomal gains involving chromosomes 1, 6-8, 18-21 and losses involving chromosomes 13, 16 and 17. Losses in chromosome 13, in particular loss in 13q14 (including RB1, RCTB2, DLEU1, and ITM2B genes), were observed in 4 out of 8 cases analyzed. Additional FISH analyses confirmed the presence of a monoallelic RB1 deletion in 8/12 cases. Moreover, nuclear Rb expression was deficient in all studied cases. None showed DDIT3 gene rearrangement or MDM2 gene amplification. Using genome-wide DNA methylation profiling, myxoid pleomorphic liposarcomas and conventional pleomorphic liposarcomas formed a common methylation cluster, which segregated from conventional myxoid liposarcomas. While the morphologic, genetic and epigenetic characteristics of myxoid pleomorphic liposarcoma suggest a link with conventional pleomorphic liposarcoma, its distinctive clinical features support continued separate classification for the time being.

GNA14, GNA11, and GNAQ Mutations Are Frequent in Benign but Not Malignant Cutaneous Vascular Tumors.

Cutaneous vascular tumors consist of a heterogeneous group of benign proliferations, including a range of hemangiomas and vascular malformations, as well as heterogeneous groups of both borderline and malignant neoplasms such as Kaposi's sarcoma and angiosarcomas. The genetics of these tumors have been assessed independently in smaller individual cohorts making comparisons difficult. In our study, we analyzed a representative cohort of benign vascular proliferations observed in a clinical routine setting as well as a selection of malignant vascular proliferations. Our cohort of 104 vascular proliferations including hemangiomas, malformations, angiosarcomas and Kaposi's sarcoma were screened by targeted next-generation sequencing for activating genetic mutations known or assumed to be potentially relevant in vascular proliferations. An association analysis was performed for mutation status and clinico-pathological parameters. Frequent activating hotspot mutations in GNA genes, including GNA14 Q205, GNA11 and GNAQ Q209 were identified in 16 of 64 benign vascular tumors (25%). GNA gene mutations were particularly frequent (52%) in cherry (senile) hemangiomas (13 of 25). In angiosarcomas, activating RAS mutations (HRAS and NRAS) were identified in three samples (16%). No activating GNA or RAS gene mutations were identified in Kaposi's sarcomas. Our study identifies GNA14 Q205, GNA11 and GNAQ Q209 mutations as being the most common and mutually exclusive mutations in benign hemangiomas. These mutations were not identified in malignant vascular tumors, which could be of potential diagnostic value in distinguishing these entities.

Bilateral Nipple Enlargement as a Secondary Effect of Anabolic Drugs: A Histopathological Mimicker of Smooth Muscle Hamartoma.

Smooth muscle hamartoma are usually solitary and congenital, may affect the genital area and nipples. Histopathologically, they are characterized by the presence of mature smooth muscle bundles. We present a 40 year-old male with bilateral nipple enlargement excised with clinical suspicion of bilateral leiomyoma. Skin biopsy shows mature, irregularly arranged smooth muscle bundles and lactiferous ducts between them. Immunohistochemistry is positive for smooth muscle actin, desmin and fumarase, but negative for estrogen and progestogen receptors. The presence of lactiferous ducts excludes bilateral leiomyomas. Even when, histopathologically, this can be interpreted as the nipple-type of muscular hamartoma of the breast, clinical history favors an anabolic drug-induced lesion. Bodybuilders present gynecomastia and nipple enlargement as frequent problems, but we have not found any histopathological description of these nipple lesions. We consider that dermatologists should be aware of the presence of them and dermatopathologists should know their histopathological features to avoid misdiagnosis as neoplasms.

Clinicopathologic and molecular analysis of embryonal rhabdomyosarcoma of the genitourinary tract: evidence for a distinct DICER1-associated subgroup.

Embryonal rhabdomyosarcoma (ERMS) of the uterus has recently been shown to frequently harbor DICER1 mutations. Interestingly, only rare cases of extrauterine DICER1-associated ERMS, mostly located in the genitourinary tract, have been reported to date. Our goal was to study clinicopathologic and molecular profiles of DICER1-mutant (DICER1-mut) and DICER1-wild type (DICER1-wt) ERMS in a cohort of genitourinary tumors. We collected a cohort of 17 ERMS including nine uterine (four uterine corpus and five cervix), one vaginal, and seven urinary tract tumors. DNA sequencing revealed mutations of DICER1 in 9/9 uterine ERMS. All other ERMS of our cohort were DICER1-wt. The median age at diagnosis of patients with DICER1-mut and DICER1-wt ERMS was 36 years and 5 years, respectively. Limited follow-up data (available for 15/17 patients) suggested that DICER1-mut ERMS might show a less aggressive clinical course than DICER1-wt ERMS. Histological features only observed in DICER1-mut ERMS were cartilaginous nodules (6/9 DICER1-mut ERMS), in one case accompanied by foci of ossification. Recurrent mutations identified in both DICER1-mut and DICER1-wt ERMS affected KRAS, NRAS, and TP53. Copy number analysis revealed similar structural variations with frequent gains on chromosomes 2, 3, and 8, independent of DICER1 mutation status. Unsupervised hierarchical clustering of array-based whole-genome DNA methylation data of our study cohort together with an extended methylation data set including different RMS subtypes from genitourinary and extra-genitourinary locations (n = 102), revealed a distinct cluster for DICER1-mut ERMS. Such tumors clearly segregated from the clusters of DICER1-wt ERMS, alveolar RMS, and MYOD1-mutant spindle cell and sclerosing RMS. Only one tumor, previously diagnosed as ERMS arising in the maxilla of a 6-year-old boy clustered with DICER1-mut ERMS of the uterus. Subsequent sequencing analysis identified two DICER1 mutations in the latter case. Our results suggest that DICER1-mut ERMS might qualify as a distinct subtype in future classifications of RMS.

Metaplastic spiradenocarcinoma: Report of two cases with sarcomatous differentiation.

Spiradenocarcinoma (SC) is a very rare malignant skin adnexal tumor with sweat gland differentiation that develops from a pre-existing spiradenoma, cylindroma, or hybrid tumor called spiradenocylindroma, or arises de novo. We present two exceptionally rare SC cases showing sarcomatous differentiation; we also discuss the clinicopathologic features of SC, as well as its differential diagnoses and available therapeutic modalities. Given the aggressive behavior of SC, rapid diagnosis and complete removal of the tumor with tumor-free margins is mandatory. Owing to the marked morphological heterogeneity of individual SC cases, dermatopathologists must be familiar with the different possible histopathologic manifestations of this neoplasm.

Molecular Diagnostics of Vascular Tumors of the Skin.

In this article, the authors have reviewed all the recent news regarding how the discovery of some novel and recurrent molecular and genetic changes has modified the classification of some entities and have addressed to the description of new variants of vascular tumors. And even more important, the authors also reviewed on how these findings, in addition to gain insight into the tumoral biology, portend significant clinical consequences not only regarding to their diagnosis but also to their management and prognosis because some of these mutations are potential targets for treatment. The authors have also highlighted immunohistochemical markers can help us as a surrogate marker of those molecular alterations.