Signet-ring cell melanoma with sentinel lymph node metastasis: A case report with immunohistochemical analysis and review of the clinicopathological features

Abstract

Signet-ring cell melanoma is an extremely rare variant of malignant melanoma. A 68-year-old male presented with a black nodule on the left thigh. Histopathological examination revealed proliferation of sheet-like or variable-sized nests of atypical melanocytes. Neoplastic cells showing signet-ring cell appearance, characterized by the presence of eccentrically located enlarged nuclei and abundant pale cytoplasm, were also present. Immunohistochemically, the tumor cells were positive for S-100 protein, vimentin and Melan-A. Moreover, mammalian target of rapamycin (mTOR) pathway proteins were diffusely expressed. The current case report presents the 21st reported case of signet-ring cell melanoma. Analyses of the clinicopathological features revealed that this disease commonly affects middle-aged males and the presence of metastatic signet-ring cell melanoma with an unknown primary tumor. Immunohistochemical analyses of melanocytic markers have been useful for establishing the diagnosis of this type of disease, however, HMB-45 is occasionally found to be negative. In addition, the present case report is the first to analyze the expression of mTOR pathway proteins, which are central proteins involved in carcinogenesis and its inhibitor has been proposed as a therapeutic target for various types of tumor. Therefore, the mTOR inhibitor may also be a potential candidate for the treatment of this type of tumor.

Primary signet ring cell carcinoma of the pancreas: Cytopathology review of a rare entity

“…In the reported case, the neoplastic cells were enlarged with ample vacuolated cytoplasm, and hyperchromatic nuclei with irregular contours and prominent nucleoli, admixed with pleomorphic mononuclear cells and multinucleated giant cells . Other scenarios that can mimic signet ring cells carcinoma in the pancreas include, but are not limited to, metastatic SRCC of another organ to the pancreas (Figure ), melanoma with signet ring cell features and signet ring cell lymphoma . Discussion of these entities is beyond the scope of this review, nonetheless caution should be applied by careful clinical investigation, to avoid misdiagnosis in the setting of a metastatic neoplasm to the pancreas, as management in this scenario is radically different from that of primary pancreatic neoplasms.…”

The Cytodiagnosis of Amelanotic Primary Signet Ring Cell Melanoma at the Unusual Site of the Axilla: A Case Report of a Rare Entity

“…Primary signet ring cell melanoma is an extremely rare variant of malignant melanoma [2]. The morphological diagnosis of the condition is based on the signetoid morphology of malignant melanocytes [2][3][4]. Therefore, signet ring cell melanoma is often associated with a potential diagnostic pitfall [7].…”

“…Signet ring cell melanoma is reported to constitute about 0.5% of all malignant melanoma cases [ 3 ]. While it usually occurs on the skin and mucosa, it is also reported at rare locations of anorectum [ 4 ] and gastroesophageal junction [ 5 ]. However, the diagnosis of primary cutaneous signet ring cell melanoma on fine needle aspiration cytology (FNAC) is rarely reported.…”

Fine‐needle aspiration of metastatic melanoma with signet‐ring cell features

“…[1][2][3] Among the numerous morphologic variants of melanoma, spindle cell, and small cell variants are relatively common, 4 whereas the signet-ring cells variant is very rare and is reported in only scant pathology literature, mostly in surgical pathology literature. [5][6][7][8] To the best of our knowledge, only one cytology report regarding a signet-ring cell melanoma in a FNA sample has been published. 9 In that case involving a groin lymph node, poorly cohesive large tumor cells showed signet-ring cell features with eccentric nuclei and abundant eosinophilic cytoplasm, some of which showed cytoplasmic melanin pigments.…”