Rare differential diagnosis: secretory carcinoma of the parotid gland.

Introduction Approximately 80% of all salivary gland tumors are found in the parotid gland, with malignancy detected in approximately 20% of cases. Most common are mucoepidermoid carcinomas, adenoid cystic carcinomas and metastases. Rarer cases are acinic cell or adenocarcinoma.

Case presentation A 36-year-old female patient presented with a slowly progressive indolent mass on the left lower pole of the parotid gland, present for months, without infection or trauma. Clinical examination with sonography revealed a 1.5x1x1.5 cm intraparotid, echo-deficient, smooth-bordered mass. The facial nerve was intact. Under the suspicion of a pleomorphic adenoma, extracapsular dissection was performed without damage to the tumor capsule. Histologic examination showed evidence of a translocation t(12;15)(p13;q25) ETV6-NTRK3. The findings were consistent with a mammary analog secretory carcinoma. Contrary to the tumor board decision with wait and see, selective neck dissection level II-IV, and partial parotidectomy were performed.

( Histology: pT1 pN0 (0/18) cM0 L0 V0 pn0 G1R0 ) Discussion tumors of the parotid gland represent a heterogeneous group, which may complicate correct diagnosis. Since its initial description in 2010, mammary analogous secretory carcinoma has been recognized as a rare differential diagnosis of malignant salivary gland tumors, which is often misdiagnosed as pleomorphic adenoma or acinic cell carcinoma. Molecular pathology demonstrates a t(12;15) (q13;q25) translocation ETV6-NTRK3. As a new and rare tumor entity, further research is needed to establish prognostic stratification and treatment pathways in the future.

Publication History

Article published online:
12 May 2023