Abstract

Background: Cylindroma/spiradenoma can rarely have foci mimicking adenoid cystic carcinoma (ACC), which, in a small biopsy, can lead to overdiagnosis. We present a case of dermal basaloid neoplasm having ACC-like features. Case: An 84yo male with a history of non-melanoma skin cancers presented with a slow-growing, pink, smooth, pearly, & non-tender papule on the right chest. A tangential biopsy was obtained to rule out nevus, neurofibroma, & non-melanoma skin cancer. Microscopic examination showed a dermal biphasic basaloid neoplasm with no epidermal connection. Some basaloid islands were back-to-back (“jigsaw-puzzle”) surrounded by a thick basement membrane & consisted of basophilic cells (periphery), larger pale cells (centrally), & hyaline droplets. Other basaloid islands consisted of basophilic cells arranged in a cribriform pattern with cystic spaces containing mucin & pink hyaline droplets. There was no marked cytologic atypia or pleomorphism. Few basaloid islands had scattered lymphocytes. The portions in the biopsy were reported as a basaloid neoplasm with sweat-gland differentiation having features of cylindroma & ACC. Excision of the remainder of the lesion showed tumor-free margins & confirmed the above-mentioned findings. The ACC-like pattern comprised ~1/3 of the tumor mass with no perineural invasion, necrosis, or subcutaneous invasion & only rare mitosis. The histologic findings were consistent with ACC-like change in the background of a cylindroma. Conclusion: Two prior publications describe 8 spiradenomas & 1 spiradenocylindroma with ACC-like features. The overlapping sweat gland origin & reports of lesions with features of spiradenoma, cylindroma, and/or ACC raise the question of a possible spectrum of disease. Given the propensity for primary cutaneous ACCs to show local recurrence & even rarely lymph node & lung metastasis, it would be prudent to ensure complete removal of lesions showing these features, especially in partially sampled cases.

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