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Desmoplastic melanoma (DM) is a variant of melanoma, which typically affects chronically sun-damaged skin of elderly patients. Pure DM displays a low density of fusiform melanocytes in a collagen-rich matrix. In mixed DM, tumor cell density is higher, and parts of the tumor lack abundant stromal fibrosis. Both pure and mixed DMs usually express S100 protein homogenously. We report herein an unusual biphenotypic tumor characterized by the association of a pure DM with an undifferentiated solid spindle cell nodule. It occurred on the scalp of a 66-year-old man. A biopsy of the undifferentiated spindle cell nodule was initially interpreted at a commercial laboratory as atypical fibroxanthoma. The pure DM was seen only in the excisional specimen. All cells of the pure DM stained for S100 protein and SOX10. The adjacent solid sarcomatoid spindle cell nodule lacked expression of S100 protein, SOX10, as well as melan-A, gp100, and microphthalmia-associated transcription factor in >95% of its tumor cells. Although focal expression of melanocyte differentiation antigens in the solid tumor component made us favor a combined DM with sarcomatoid dedifferentiation, we also considered the possibility of a collision scenario, that is, a pleomorphic dermal sarcoma incidentally colliding with a DM. To further assess a possible relationship of the sarcomatoid nodule with the DM, we performed next-generation sequencing analysis on each component separately. The analysis revealed shared chromosomal copy number changes and a high number of common mutations, thereby supporting the concept of a DM with a dedifferentiated sarcomatoid component. An interesting finding is the presence of mutations of the neurofibromin 1 (NF1) gene in both tumor components.

Abstract Background Combined hepatocellular-cholangiocarcinoma (cHCC-CC) is a rare primary liver tumor, which has overlapping imaging features with mass forming intra-hepatic cholangiocarcinoma (ICC) and hepatocellular carcinoma (HCC). Previous studies reported imaging features more closely resemble ICC and the aim of our study was to examine the differential MRI features of cHCC-CC and ICC with emphasis on enhancement pattern observations of gadolinium enhanced MRI. Methods Institutional review board approval with consent waiver was obtained for this retrospective bi-centric study. Thirty-three patients with pathologically proven cHCC-CC and thirty-eight patients with pathologically proven ICC, who had pre-operative MRI, were identified. MRI images were analyzed for tumor location and size, T1 and T2 signal characteristics, the presence/absence of: cirrhosis, intra-lesional fat, hemorrhage/hemosiderin, scar, capsular retraction, tumor thrombus, biliary dilatation, degree of arterial enhancement, enhancement pattern, pseudocapsule and washout. Associations between MRI features and tumor type were examined using the Fisher’s exact and chi-square tests. Results Strong arterial phase enhancement and the presence of: washout, washout and progression, intra-lesional fat and hemorrhage were all strongly associated with cHCC-CC (P

Purpose of Review: To review the recent consensus on the nomenclature, clinical features, diagnosis, and treatment of combined hepatocellular carcinoma-cholangiocarcinoma (cHCC-CCA).Recent Findings: cHCC-CCA is a primary liver carcinoma with varying degrees of hepatocytic and cholangiocytic cytology and architecture within the same tumor. The diagnosis of cHCC-CCA can only be established based on histologic examination. Surgical resection should be considered in patients with resectable tumors who do not have underlying liver disease or clinically significant portal hypertension. While treatment by liver transplantation (LT) is controversial due to the high risk of post-LT recurrence, LT should remain as a potentially curative option in a highly selected group of patients. Little data exist for the outcome of other treatments.Summary: High-quality multicenter prospective studies should be conducted to better understand this rare but increasingly recognized tumor. [ABSTRACT FROM AUTHOR]