Numb chin syndrome leads to diagnosis of metastatic carcinoma: Case Report

Background: Charles Bell first reported numb chin syndrome in a patient with known breast cancer. It remains an important clinical sign for metastatic carcinoma and rheumatological disease causing mass lesions. Case presentation: 72-year-old-female with history of newly diagnosed diabetes who presented to the emergency room with two days of right peripheral facial palsy and lack of sensation to light touch and pinprick in the right mental nerve distribution. Computer tomography (CT) head and CT angiographic imaging of head and neck were normal from neurological perspective, but demonstrated a 1.9 cm irregular solid left apical lung nodule and cervical lymphadenopathy along the right jugular vein, including a necrotic lymph node. MRI demonstrated 3.8 cm enhancing submandibular neck mass. Marrow enhancement and edema within the right aspect of the mandible concerning for osseous involvement of disease. CT guided biopsy of nodular mass of left upper lung was consistent with adenoid cystic carcinoma with small, angulated cells positive for cytokeratin AE1/AE3, p40, and CD117. The diagnosis from submandibular biopsy was adenoid cystic carcinoma, cribriform and tubular pattern, high grade, with features of “dedifferentiation.” Staging was based on American Joint Committee on Cancer (AJCC) 8 ^th Edition pathological tumor node metastasis (pTNM) as pT4a, pN3b, pM (unable to determine). She subsequently was treated with 4 radiation treatments to the right mandibular area (2A HN), with 370 cGy each, for total dose of 1480 cGy. She remains with persistent sensory loss and facial weakness. Conclusion : Recognition of numb chin syndrome allowed the patient to get appropriate diagnostic tests. Possible primary right submandibular gland tumor with extension into the mandible likely pressed on the inferior alveolar nerve and its mental nerve branch. Possible parotid involvement could have caused pressure on the facial nerve.