Diagnosis of secretory carcinoma of the upper lip: A rare case report and literature review.

Secretory carcinoma (SC) is a rare malignant neoplasm of the salivary glands, first recognized in 2010 due to its resemblance to secretory breast carcinoma. Although classified as a low-grade tumor with generally favorable outcomes, some cases may exhibit high-grade features, including lymph node metastasis and aggressive histological architecture. The defining characteristic of SC is the ETV6-NTRK3 gene fusion; however, diagnosis can also rely on histopathological and immunohistochemical criteria when this fusion is absent. SC typically requires complete surgical excision with negative margins, with adjuvant radiotherapy considered in selected cases. Occurrence of SC in the upper lip is extremely rare, particularly in female patients, making accurate diagnosis essential. A 50-year-old woman with a history of sinusitis, arthritis, hypercholesterolemia, and thyroid nodules presented with a slow-growing, painless nodule on the upper labial mucosa. Clinically, the lesion resembled a benign mucocele. Histopathological analysis revealed a fibrous capsule surrounding proliferating cells with eosinophilic cytoplasm and a predominantly microcystic pattern with some papillary features. Immunohistochemistry confirmed SC, with strong positivity for CK7, S100, and mammaglobin, and negativity for CK14 and p63. Complete surgical excision was performed, and no residual tumor was found. Follow-up over nine months showed no recurrence. This case highlights the importance of recognizing SC in atypical locations, such as the upper lip. Given its clinical similarity to benign conditions like mucocele, thorough histopathological and immunohistochemical analyses are crucial. Early identification and complete excision are key to achieving favorable outcomes.