Epithelial sheath neuroma is a rarely recognized but established entity in the medical literature. First described in 2000 by Requena et al, there have only been 7 published cases to date, mostly in female patients and presenting as symptomatic solitary lesions on the back without a known history of trauma. In 2006, Beer et al described and reviewed a dozen cases in which epithelial sheath neuroma-like features were seen in the advent of a surgical procedure, which was termed "re-excision perineural invasion" and attributed to possible eccrine duct implantation during surgery. Our case is a 66-year-old male patient who underwent an excision of a melanocytic neoplasm in which a reactive epithelial sheath neuroma was incidentally discovered in the excision specimen, adjacent to the biopsy site cicatrix. Histologically, there was benign cutaneous nerve hyperplasia with a proliferation of squamous epithelium in intimate apposition to the nerve bundles in the superficial dermis. We postulate that the process active in the formation of re-excision perineural invasion is the same as in epithelial sheath neuroma and that minor trauma not appreciable on histologic examination is responsible in the latter entity. We performed IL-6 staining and documented that IL-6 was upregulated at the interface of the nerve and reactive epithelium, but was absent in nerves distant from the site of surgery, suggesting that IL-6 may be essential to the lesion's development. The recognition of reactive epithelial sheath neuroma including the subcategory of re-excision perineural invasion is crucial for the dermatopathologist to prevent mislabeling this reactive entity as a perineural squamous cell carcinoma, which has clinical consequences for the patient such as wider re-excision and radiation treatment. Additionally, we have identified a potential pathophysiologic basis for this lesion.
De novo intraepidermal epithelioid melanocytic dysplasia represents a distinctive form of intraepidermal melanocytic dysplasia. Although these lesions are atypical, they are not diagnostic of melanoma. They are considered a part of the atypical mole phenotype and may define a point in the natural course of melanomagenesis.
We report 2 cases which shared an unusual histopathologic pattern of a xanthomatous infiltrate occurring on the nose. Both patients were women in their fifth decade. Each presented to the dermatology clinic with multiple soft, flesh-colored papules, up to 1 cm, in diameter on the lateral aspects of the nose. The lesions had been present for several years. Both patients were otherwise completely well, and asymptomatic. In one case, focal telangiectasia and central umbilication was noted, and the clinical differential diagnoses included basal cell carcinomas and appendageal tumors. In each case, a biopsy was performed. The lesions appeared histologically quite similar. The epidermis was unremarkable. Within the dermis, there was a mid-reticular dermal infiltrate of macrophages with unilocular and multilocular fat laden cytoplasm, and scalloped nuclei. Only a scant inflammatory infiltrate of lymphocytes and histiocytes was present. Minimal dermal fibrosis was also present. We believe that xanthomatous infiltrate of the face is a distinct clinical entity which presents as multiple flesh-colored papules on the nose, which have a characteristic histologic appearance of abundant lipid-laden macrophages within the dermis.
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