Tumoral melanosis mimicking residual melanoma in the setting of talimogene laherparepvec treatment.

Talimogene laherparepvec (T-VEC) has become an increasingly popular treatment option for surgically non-resectable, recurrent melanoma, usually of cutaneous metastases. The complete response (CR) rate has been reported to be ~20% with a median of ~9 months to achieve it. In real-world practice, decrease of tumor size often occurs rapidly within the first 2-3 months, while improvement of the pigmentation takes several more months. Such clinical observation of lasting pigmentation could be explained by tumorous melanosis-a histopathological term referring to the presence of a melanophage-rich inflammatory infiltrate without remaining viable tumor cells. Herein, we report six patients with metastatic cutaneous melanoma who were treated with T-VEC. Biopsies were performed after observing clinical responses in the injected tumors. Pathological evaluation demonstrated non-viable or absent tumor tissue with tumorous melanosis in all cases. To accurately assess response to therapy and potentially decrease unnecessary additional T-VEC treatments, serial biopsy of 'stable' lesions should be considered to assess the presence or absence of viable tumor.

A case of endocrine mucin-producing sweat gland carcinoma with distant metastasis.

Endocrine mucin-producing sweat gland carcinoma (EMPSGC) is a rare cutaneous adnexal neoplasm typically arising on the face of older individuals, most commonly around the eyelids. Histopathologic features include a circumscribed proliferation of low-grade epithelioid cells with areas of cystic and cribriform growth, foci of intracytoplasmic and extracellular mucin, and coexpression of endocrine, neuroendocrine, and cytokeratin markers by immunohistochemistry. Given histopathologic and immunohistochemical similarities, EMPSGC is often likened to solid papillary carcinoma of the breast and endocrine ductal carcinoma in situ, and is thought by many to represent a forme fruste of mucinous carcinoma of the skin. To date, the vast majority of reported cases of EMPSGC have been described as having indolent behavior, with no cases of distant metastasis yet reported. Here we report a unique case of EMPSGC that recurred over several years following standard surgical excision and Mohs micrographic surgery, with subsequent metastasis to the parotid gland and axial skeleton.

Impact of clinical photographs on the accuracy and confidence in the histopathological diagnosis of mycosis fungoides.

BACKGROUND: The histopathological diagnosis of MF is challenging, and there is significant overlap with benign inflammatory processes. Clinical features may be relevant in the assessment of skin biopsies. METHODS: We provided photomicrographs to board-certified dermatopathologists and one hematopathologist with and without accompanying clinical photographs and assessed accuracy and confidence in diagnosing MF. RESULTS: We found that access to clinical photographs improved diagnostic accuracy in both MF and non-MF (distractors); the degree of improvement was significantly higher in the non-MF/distractor category. Across all categories, diagnostic confidence level was higher when clinical images were available. CONCLUSION: These findings suggest that clinical images are useful in making an accurate diagnosis of MF, and may be particularly helpful in ruling it out when an inflammatory disorder is clinically suspected.

Utility of glutamine synthetase immunohistochemistry in identifying features of regressed cirrhosis.

The prevailing view that cirrhosis is irreversible has been challenged. It has been proposed that varying degrees of fibrosis regression can be achieved if the injurious agent is removed. In the normal liver, glutamine synthetase immunostaining is present around central veins. In regressed cirrhosis, although fibrous bands between portal tracts and central veins may largely be resorbed, the abnormal portal tract-central vein adherence often remains. Hence, we hypothesized that aberrant glutamine synthetase positivity adjacent to portal tracts would help identify regressed cirrhosis. We performed glutamine synthetase immunohistochemistry on 49 liver specimens (16 regressed cirrhosis, 18 cirrhotic, and 15 normal livers). Qualification for regressed cirrhosis required the following histologic features: curved, delicate incomplete septa, portal tract-central vein adhesions, and portal tract "remnants" (portal tracts with no venous branch). Out of 16, 14 regressed cirrhosis cases had baseline cirrhosis established based on previous biopsy or signs of cirrhosis based on physical exam, laboratory, and radiological findings. All regressed cirrhosis cases (100%) had areas of aberrant glutamine synthetase positivity adjacent to portal tracts, indicating that portal tract-central vein approximation had occurred (p < 0.001 compared to all other categories). No normal cases had glutamine synthetase positivity adjacent to portal tracts, and half of cirrhosis cases had areas showing features of regression, with focal glutamine synthetase positivity adjacent to portal tracts. Overall, glutamine synthetase expression showed highly significant differences among the three categories (p < 0.001). This study shows that aberrant glutamine synthetase positivity adjacent to portal tracts is present in regressed cirrhosis and can be useful in identifying regressed cirrhosis when it is histologically suspected.

Heterotopic atypical trophoblasts mimicking ectopic choriocarcinoma coexistent with a viable intrauterine pregnancy: A diagnostic dilemma.

•Ectopic choriocarcinoma coexistent with viable IUP is rare but has been reported.•Atypical and proliferative trophoblasts are normal in an early conceptus.•Evaluation including MRI and CXR did not reveal metastatic choriocarcinoma.•IHC analysis for p57, molecular genotyping of DNA microsatellites was performed.•ß-hCGs appropriately rose then plateaued; remainder of pregnancy was unremarkable.