Shon, Wonwoo

Mammary analog secretory carcinoma of salivary glands is a relatively recently recognized entity that harbors the ETV6‐NTRK3 fusion transcript. To date, only rare cases of mammary analog secretory carcinoma of the skin have been reported. A 57‐year‐old man presented with a 6.0 cm cystic mass in the axilla, involving the dermis and superficial subcutis. Microscopically, the tumor exhibited nodular aggregation of tubular and microcystic structures embedded in the dense fibrotic and hyalinized stroma. Characteristic ‘colloid‐like’ eosinophilic secretory material was present within intraluminal spaces. Tumor cells were largely characterized by vesicular nuclei with inconspicuous nucleoli and pink vacuolated cytoplasm. With respect to immunohistochemistry, tumor cells were intensely positive for AE1/AE3, Cam 5.2, and CK7, whereas Ber‐EP4 and CEA were completely negative. A dual color break‐apart fluorescence in situ hybridization probe identified rearrangement of the ETV6 gene locus on chromosome 12. The patient is alive with no evidence of recurrent disease or metastasis 3 years after the initial surgery. In conclusion, we report a rare example of mammary analog secretory carcinoma of the skin with ETV6 rearrangement. Awareness of this unique cutaneous tumor and subsequent reporting of additional cases is necessary for better characterization of its completely clinicopathologic spectrum.

Background. Malignant melanoma of the nail apparatus is exceedingly rare. Increasingly, genetic studies have been employed to aid in distinguishing between malignant melanoma and benign melanocytic nevi. Methods. Archived nail apparatus melanomas were analyzed by fluorescence in situ hybridization (FISH) using probes targeting the genes at 6p25 (RREB1), 11q13 (CCND1), 8q24.1 (MYC), 6q23 (MYB), 9p21 (CDKN2A) and the centromeres of chromosomes 8 (D8Z2) and 6 (D6Z1). The results were correlated with clinical and demographic information. Results. Mean patient age was 57.8 years (range 23-92 years). In all, 5 of 7 (71%) cases involved the upper extremity digits. RREB1 gain was seen in all cases. CCND1 gain was seen in 6 of 7 (86%) cases, 3 of which were amplified. MYB loss and MYC gain were both seen in 5 of 7 (71%) cases. Homozygous loss of CDKN2A was not observed in any case. Two of 7 (28.6%) patients had lymph node metastasis and died of widely metastatic disease. These 2 patients harbored the most genetic aberrations: gains of RREB1, CCND1, and MYC, and MYB loss. Both benign melanocytic nevi controls showed normal FISH results. Conclusions. RREB1 and CCND1 gains are common in nail apparatus melanoma as in most melanomas, and an increased number of genetic aberrations may be associated with a poorer prognosis, though the limited number of cases precludes definitive correlation. FISH appears to be a useful adjunct in the diagnosis of nail apparatus melanomas and improves diagnostic confidence even in the setting of unambiguous histomorphology.

SummaryPerivascular epithelioid cell neoplasms (PEComas) are a group of mesenchymal tumours with concurrent melanocytic and myogenic differentiation. Although many cases are sporadic, PEComas can be associated with tuberous sclerosis. A distinct subset of deep-seated PEComas has been shown to carry TFE3 fusions. To our knowledge, this is the first reported case of primary subcutaneous malignant PEComa with molecular confirmation of TFE3 gene rearrangement.

Aim We studied ERG expression in a large series of chondrogenic bone and soft tissue tumours to assess the value of ERG as a possible marker of chondroid/cartilaginous differentiation. Methods Formalin-fixed, paraffin-embedded whole sections from 111 bone and soft tissue tumours with chondroid differentiation or a morphology that may mimic cartilaginous differentiation were retrieved. Immunohistochemistry was performed using anti-ERG monoclonal antibody directed against the N terminus. Nuclear staining was scored as negative (<5%), 1+ (5%–25%), 2+ (26%–50%), 3+ (>51%). Results Nuclear ERG expression was seen in all cases of soft tissue chondroma (8), chondromyxoid fibroma (7), chondroblastic osteosarcoma (6) and clear cell chondrosarcoma (1). 10/12 conventional chondrosarcomas were also positive for ERG. In cases of dedifferentiated chondrosarcoma, the well-differentiated component was positive in 7/9 cases, while all dedifferentiated foci were negative. In cases of mesenchymal chondrosarcoma, the hyaline cartilage component was positive in 2/4 cases, whereas the primitive component in all cases was negative. Variable positivity was identified in extraskeletal myxoid chondrosarcomas (4/9), chondroblastomas (3/8) and mixed tumours/myoepitheliomas (2/11). Only 1/12 chordoma was positive for ERG (1+). Interestingly, 15/17 enchondromas were negative for ERG. Conclusions In this study, we further characterise the expression of ERG in mesenchymal tumours and found relatively constant nuclear ERG expression in selected chondrogenic tumours including conventional chondrosarcoma, chondromyxoid fibroma, chondroblastic osteosarcoma and clear cell chondrosarcoma. We also show that ERG may be a helpful ancillary tool in certain select diagnostic scenarios and that awareness of ERG expression in tumours with cartilaginous differentiation is important.

AbstractBackgroundEndocrine mucin‐producing sweat gland carcinoma (EMPSGC), a low‐grade sweat gland carcinoma with a predilection for the eyelids, often shows areas of benign eccrine cysts, atypical intracystic proliferation and associated mucinous carcinoma, suggesting tumor progression. Wilms tumor 1 (WT1) protein, a transcription factor, is overexpressed in many tumors and plays a role in oncogenesis.MethodsA computer‐based search for tumors diagnosed between 1989 and 2009 was conducted. Clinical data were obtained from pathology reports and patient records. Biopsies were reviewed for histologic features. Immunostaining was performed for WT1, chromogranin, synaptophysin, estrogen receptor (ER), epithelial membrane antigen (EMA), polyclonal carcinoembryonic antigen (P‐CEA), cytokeratin 7 (CK7), cytokeratin 20 (CK20) and MIB‐1.ResultsEight women and five men (mean age: 61.2 years; range: 40–77 years) presented with slow‐growing eyelid nodules. Cases of EMPSGC were characterized by the presence of dermal nodules with various growth patterns. Adjacent eccrine cysts were present in five patients, atypical epithelial proliferation within the cyst wall in four patients, and an associated mucinous carcinoma in one patient. All tumors were positive for WT1, CK7, ER, P‐CEA and EMA and negative for CK20. Tumors were positive for synaptophysin in 12 cases and chromogranin in nine cases. The MIB‐1 proliferation index was low in most cases. No WT1 staining was observed in the overlying epidermis, adnexal structures or areas of benign eccrine cyst. WT1 expression was observed in areas of atypical epithelial proliferation, and the neoplastic cells.ConclusionsThe present study shows WT1 expression in the neoplastic epithelial cells of EMPSGC, areas of atypical intraductal proliferations, and mucinous carcinoma. The absence of WT1 expression in areas of benign eccrine cyst and cutaneous sweat glands suggests WT1 upregulation plays a role in tumor cell proliferation and progression of EMPSGC.

Generalized eruptive histiocytosis, described in 1963 by Winklemann and Muller, is a reactive, self‐healing form of non‐Langerhans histiocytosis. Rare cases of atypical generalized eruptive histiocytosis have been reported in patients with hematopoietic malignancy, but the biological relationship between the two disorders is not known. We report an 84‐year‐old man with chronic myelomonocytic leukemia who presented with coalescing erythematous papules and plaques on the posterior neck, ear and lower lip, followed by development of blast crisis. Skin biopsy revealed a thick band‐like dermal infiltrate of cells that exhibited morphologic features of macrophages or histiocytes and prominent elastolytic phagocytosis. These cells demonstrated a mature immunophenotype, expressing CD14 and CD68, with partial expression of CD13 but not CD1a, CD43, CD56, CD123, Langerin, or S‐100 protein. Karyotype and fluorescence in situ hybridization analyses showed loss of the Y chromosome in bone marrow and skin specimens, providing evidence of a clonal relationship between the cutaneous eruption and the underlying chronic myelomonocytic leukemia. The presence of the same clone in skin and bone marrow specimens from our patient supports the possibility that atypical generalized eruptive histiocytosis is a marker for underlying hematopoietic malignancy. Discovery of additional cases may shed further light on the pathogenesis of this rare entity.