Secretory carcinoma

Secretory carcinoma (SC), also known as mammary analog secretory carcinoma (MASC), is a rare type of cancer that primarily arises in the salivary glands. It was first identified in the breast where it is known as secretory breast carcinoma. This malignancy is characterized by its resemblance to secretory carcinoma of the breast, hence the name "mammary analog." It is most commonly found in the parotid gland, the largest of the salivary glands, but can also occur in other minor salivary glands throughout the body.

Etiology and Pathogenesis

The etiology of secretory carcinoma is not fully understood, but it is known to involve a translocation between chromosomes 12 and 15, resulting in the ETV6-NTRK3 gene fusion. This genetic alteration is believed to play a crucial role in the development of SC by promoting cellular growth and survival. The ETV6-NTRK3 fusion gene is a characteristic feature of SC, making it a useful diagnostic marker.

Clinical Presentation

Patients with secretory carcinoma typically present with a painless, slow-growing mass in the affected salivary gland. The tumor can occur at any age but has a slight male predominance. Due to its slow growth, SC may not cause significant symptoms until it reaches a considerable size. In some cases, facial nerve weakness or paralysis may occur if the tumor involves or compresses the facial nerve.

Diagnosis

The diagnosis of secretory carcinoma is based on a combination of clinical examination, imaging studies, and histopathological analysis. Imaging techniques such as ultrasound, computed tomography (CT), and magnetic resonance imaging (MRI) can help in assessing the size and extent of the tumor. However, a definitive diagnosis requires a biopsy of the tumor tissue, followed by microscopic examination and immunohistochemical staining. The presence of the ETV6-NTRK3 fusion gene can be confirmed through molecular testing, which is crucial for accurate diagnosis.

Treatment

The mainstay of treatment for secretory carcinoma is surgical resection, with the goal of removing the tumor completely while preserving as much normal tissue and function as possible. In cases where the tumor is large or has spread to nearby structures, radiotherapy may be used as an adjunct to surgery. The role of chemotherapy in the treatment of SC is still under investigation, but it may be considered in advanced cases or when the tumor shows aggressive behavior.

Prognosis

The prognosis for patients with secretory carcinoma is generally favorable, especially when the tumor is detected early and completely removed. However, the outcome can vary depending on factors such as the size and location of the tumor, the presence of metastasis, and the patient's overall health. Regular follow-up is important to monitor for recurrence or the development of new tumors.

Epidemiology

Secretory carcinoma is a rare entity, accounting for a small fraction of all salivary gland tumors. It can occur at any age but is most commonly diagnosed in adults. There is a slight male predominance in the incidence of SC.

NIH genetic and rare disease info

• NIH info on Secretory carcinoma

Secretory carcinoma is a rare disease.