Primary mucinous adenocarcinoma of the scalp: A case report and literature review

• Primary mucinous adenocarcinoma of the skin is a rare tumour.
• Distinguishing between this primary neoplasm and the more frequently encountered metastatic mucinous deposits on the skin from primaries elsewhere is a diagnostic dilemma.
• Because of the high rate of recurrence, adequate excision with wide margins is advocated. Moh’s micrographic surgery can be a particularly advantageous treatment modality in this setting.
• Proper patient counselling and follow-up are important in treating this low-grade, indolent and frequently recurring tumour.

IntroductionPrimary mucinous adenocarcinoma or mucinous eccrine carcinoma of the skin is a rare malignant neoplasm showing predilection to the head and neck. Distinguishing between these primary neoplasms and the more frequent metastatic mucinous deposits on the skin from primaries in the breast and gastrointestinal tract constitutes a diagnostic dilemma.Presentation of caseWe report a case of a 61-year-old lady who presented with a slow-growing, painless scalp nodule. Upon excision, it was diagnosed as “primary mucinous adenocarcinoma”. An extensive work-up in search for another primary tumour failed to show a primary malignancy elsewhere and the diagnosis of a primary eccrine mucinous adenocarcinoma of the skin was rendered.DiscussionA review of the literature on this entity is presented, discussing diagnostic challenges and therapeutic options that of interest to surgeons, pathologists and dermatologists.ConclusionThese tumours are indolent and low-grade, with a tendency for local, sometimes multiple, recurrences. Proper patient counselling and follow-up are important in treatment. Sound collaboration between clinicians and pathologists, for good therapeutic results, is of utmost importance.