Background: Mammary analogue secretory carcinoma (MASC) is a rare low-grade malignant salivary gland tumor. The morphological and immunohistochemical features of MASC closely resemble those of breast secretory carcinoma. The key characteristics of the lesion are a lack of pain and slow growth. There is no obvious specificity in the clinical manifestations and imaging features. The diagnosis of the disease mainly depends on the detection of the MASC-specific ETV6-NTRK3 fusion gene.
Case summary: This report describes a rare case of a 32-year-old male patient who presented with a gradually growing lesion that was initially diagnosed as breast-like secretory carcinoma of the right parotid gland. Imaging and histological investigations were used to overcome the diagnostic difficulties. The lesion was managed with right parotidectomy, facial nerve preservation, biological patch implantation to restore the resulting defect, and postoperative radiotherapy. On postoperative follow-up, the patient reported a mild facial deformity with no complications, signs of facial paralysis, or Frey's syndrome.
Conclusion: The imaging and histological diagnostic challenges for MASC are discussed.
Keywords: Case report; Immunohistochemistry; Mammary analogue secretory carcinoma; Salivary gland; Total lobectomy of right parotid gland.
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