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Case Reports

Abstract

Background: Cellular Neurothekeomas are benign neoplasms with an unknown etiology, thought to be related to nerve sheath myxomas. Often, they may be challenging to distinguish from plexiform fibrohistiocytic tumors, schwannomas, and even nevoid melanomas. Herein, we describe a case where this neoplasm mimicked a Renal Cell Carcinoma (RCC) metastasis.  

Case Presentation: A 67-year-old woman with a history of RCC presented to dermatology with a 1-year history of a violaceous, tender nodule on the right posterior ankle. Shave biopsy revealed intradermal nests and fascicles of round to oval cells with monomorphic nuclei and were associated with mucin and thickened collagen bundles Based on histopathologic examination, there was concern for possible RCC metastasis; however, immunohistochemistry showed positivity for NKI/C3 and negativity for S100, SOX-10, PAX8, CD163, and PanCK, supporting a diagnosis of CN.   

Conclusion: Cellular neurothekeomas are uncommon neoplasms that may mimic more sinister entities such as cutaneous metastasis. Targeted additional studies through judicious use of immunohistochemistry are crucial to elucidate the diagnosis.