Adipophilin is a monoclonal antibody against a protein on the surface of intracellular lipid droplets, and it was recently shown to be expressed in sebocytes and sebaceous lesions. This study examines adipophilin expression in various sebaceous lesions and other cutaneous tumors with a clear cell histology that may mimic sebaceous differentiation. A total of 117 cutaneous clear cell lesions including 16 sebaceous adenomas, 25 sebaceous carcinomas, 8 basal cell carcinomas, 12 squamous cell carcinomas, 6 xanthomas, 10 xanthelasmas, 10 xanthogranulomas, 4 balloon cell nevi, 5 trichilemmomas, 8 clear cell hidradenomas, and 13 metastatic renal cell carcinomas were examined using immunohistochemistry for the expression of adipophilin. Of these 117 lesions, 42 (36%) were from the periocular region. Adipophilin was expressed in 16 of 16 (100%) sebaceous adenomas, 23 of 25 (92%) sebaceous carcinomas, 10 of 10 (100%) xanthelasmas, 9 of 10 (90%) xanthogranulomas, 6 of 6 (100%) xanthomas, and 9 of 13 (62.5%) metastatic renal cell carcinomas. The characteristic staining pattern differed between sebaceous and non-sebaceous tumors with the former showing a membranous vesicular pattern and the latter being more granular. Adipophilin expression was not seen in any of the other lesions with clear cell histology, basal cell carcinomas, or squamous cell carcinomas, including cases that had focal clear cell differentiation. Adipophilin can be valuable in an immunohistochemical panel when evaluating cutaneous lesions with clear cell histology as it identifies intracytoplasmic lipid vesicles in sebaceous and xanthomatous lesions. In periocular lesions, it is effective in helping to exclude basal cell carcinoma and squamous cell carcinoma when sebaceous carcinoma is under consideration. Adipophilin expression is not as useful for the differential diagnosis that includes metastatic renal cell carcinoma, a rare but important, diagnostic differential. The pattern of adipophilin reactivity is important to observe as membranous vesicular staining is suggestive of intracellular lipids whereas granular cytoplasmic reactivity is not. Modern Pathology (2010) 23, 567-573; doi:10.1038/modpathol.2010.1; published online 29 January 2010Keywords: adipophilin; sebaceous tumors; differential diagnosis Sebaceous carcinoma is a relatively uncommon tumor comprising 0.05% of all cutaneous malignancies, but is the second or third most common malignant eyelid tumor in most series accounting for 2-4% of periocular tumors. 1 Local recurrence complicates 6-29% of periocular sebaceous cell carcinomas. [2][3][4][5] Regional or distal metastases affect 14-25% of patients with an associated 5-year mortality ranging from 30 to 67% according to different reports. 2,4 Owing to its variable clinical appearance, sebaceous carcinoma mimics both benign processes, such as chalazions and blepharitis, and other malignant

Melanocytes accumulate galectin-3 with tumor progression, particularly in the nucleus. The strong association of cytoplasmic and nuclear expression in lesions of sun-exposed areas suggests an involvement of UV light in activation of galectin-3.

BACKGROUNDRecently, a 23‐gene signature was developed to produce a melanoma diagnostic score capable of differentiating malignant and benign melanocytic lesions. The primary objective of this study was to independently assess the ability of the gene signature to differentiate melanoma from benign nevi in clinically relevant lesions.METHODSA set of 1400 melanocytic lesions was selected from samples prospectively submitted for gene expression testing at a clinical laboratory. Each sample was tested and subjected to an independent histopathologic evaluation by 3 experienced dermatopathologists. A primary diagnosis (benign or malignant) was assigned to each sample, and diagnostic concordance among the 3 dermatopathologists was required for inclusion in analyses. The sensitivity and specificity of the score in differentiating benign and malignant melanocytic lesions were calculated to assess the association between the score and the pathologic diagnosis.RESULTSThe gene expression signature differentiated benign nevi from malignant melanoma with a sensitivity of 91.5% and a specificity of 92.5%.CONCLUSIONSThese results reflect the performance of the gene signature in a diverse array of samples encountered in routine clinical practice. Cancer 2017;123:617–628. © 2016 American Cancer Society.

To assess the diagnostic accuracy of margin evaluation of melanocytic lesions using en face frozen sections compared with standard paraffin-embedded sections, we studied 2 sets of lesions in which en face frozen sections were used for analysis of surgical margins (13 from malignant melanomas [MMs] and 10 from nonmelanocytic lesions [NMLs]). Routine permanent sections were cut after routine processing. The slides were mixed and coded randomly. Fifteen dermatopathologists examined the cases separately. Margin status was categorized as positive, negative, or indeterminate. Kappa statistics were calculated per dermatopathologist and per case. One case from each group was excluded because epidermis was not available in the routine sections. Of 330 evaluations (22 cases, 15 dermatopathologists), there were 132 diagnostic discrepancies (40.0%): 66 each for MM and NML (mean per case for both diagnoses, 6). In 9 instances (6.8%), the change was from positive (frozen) to negative (permanent) and in 43 (32.6%), from negative (frozen) to positive (permanent). There was poor agreement between frozen and permanent sections (kappa range per dermatopathologist, -0.1282 to 0.6615). If permanent histology is considered the "gold standard" for histologic evaluation, en face frozen sections are not suitable for accurate surgical margin assessment of melanocytic lesions.