Abstract
Mucinous metaplasia (goblet cell type) is an uncommon finding and exceptionally rare in the skin. Herein is the second case of apocrine papillary hidrocystoma with mucinous metaplasia (goblet cell type) and a review of the literature exploring the significance and frequency of mucinous metaplasia with goblet cells in non-genital skin. The patient is an elderly male who presented with a blue pigmented nodule on the scalp that was clinically concerning for an atypical nevus. Histologically, the lesion was composed of a simple cyst of cuboidal cells with decapitation secretion and mucinous metaplasia with goblet cells. Papillary formations were identified in the cyst. Most cases of cutaneous mucinous metaplasia are reported on genital skin and usually after chronic inflammation of the area. This type of mucinous metaplasia is categorized as benign mucinous metaplasia of the genitalia (BMM) and thought not to be related to apocrine glands due to the different histologic features and absence of apocrine differentiation by immunohistochemistry. Mucinous metaplasia (goblet cell type) has been previously reported in benign adnexal tumors (eccrine acrospiroma / hidroadenoma, mixed tumor, and syringocystadenoma papilliferum) and malignant tumors (apocrine hidradenocarcinoma and squamous cell carcinoma). To date mucinous metaplasia has not been identified in histologically normal apocrine glands.
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