Breast carcinoma metastasis to the submandibular gland: Clinical, sonographic and pathological findings of a rare entity.

Introduction: Metastatic disease to the submandibular gland is a rare phenomenon with limited information available on related imaging findings.

Case presentation: We report a 59-year-old female who presented with a palpable nodule in the right submandibular gland 6 years after treatment for breast carcinoma. Ultrasound findings were concerning for distant metastatic disease from breast cancer recurrence. The histopathological analysis of the biopsied tissue confirmed infiltration of the right submandibular gland with an adenocarcinoma from a breast primary.

Discussion: Metastatic spread to the major salivary glands is relatively uncommon with a predilection to the parotid gland owing to its extensive intraglandular lymphatic system. Conversely, metastasis to the submandibular gland, which lacks intraglandular lymph nodes, is rare. Ultrasound is the optimal first-line imaging modality to aid in the assessment of submandibular gland disease. Malignant lesions often appear hypoechoic with heterogenous internal architecture and ill-defined borders. However, some low-grade malignancies, can have apparently benign features particularly when smaller in size. Where a focal submandibular gland lesion is identified and neoplasm is suspected, the early use of ultrasound-guided core biopsy is recommended to improve diagnostic yield for histological assessment.

Conclusion: While submandibular metastasis is rare, clinical assessment, sonographic findings and use of core needle biopsy aid in prompt diagnosis and management.