A Rare Case of Stage IV Basaloid Squamous Cell Cancer with Intrapulmonary and Brain Metastases.

BACKGROUND Metastatic basaloid squamous cell carcinoma is a fatal, high-grade variant of squamous cell carcinoma that is extremely rare in the oral cavity. We present a rare case of metastatic basaloid squamous cell carcinoma arising from the hypopharynx with pulmonary and brain metastases. Recognizing this diagnostic subtype is of critical importance due to the aggressive nature and high incidence of recurrence, lymph node metastases, and mortality. CASE REPORT A 42-year-old male arrived at the Emergency Department reporting a 1-week headache. Six months prior, he reported throat pain and neck swelling. Triple endoscopy revealed a large ulcerative tumor. A carbon dioxide laser procedure debulked and removed the mass. Incisional biopsy with histopathology was consistent with invasive basaloid squamous cell carcinoma. Computed tomography (CT) of the neck with contrast demonstrated bilateral cervical level II/III necrotic adenopathy, and CT chest with contrast demonstrated bilateral pulmonary nodules. The patient completed chemoradiation therapy with cisplatin; however, repeat CT chest revealed enlarging intrapulmonary metastases. CT brain without contrast demonstrated a central brainstem lesion. The patient started treatment with pembrolizumab. On day 14 of treatment, he presented to the Emergency Department again for headache. MRI of brain with contrast demonstrated a new lesion with vasogenic edema. Intravenous dexamethasone was started and the decision to pursue stereotactic radiosurgery was made. CONCLUSIONS The diagnosis of basaloid squamous cell carcinoma in the setting of intrapulmonary and brain metastases is an extremely rare, high-grade bimorphic aggressive variant of squamous cell carcinoma that needs to be histopathologically differentiated from other tumors. Given its high mortality rate and poor prognosis the decision to pursue further treatment versus aggressive palliative care should be discussed.