Not always cancer-Probable Lyme disease mimicking squamous cell carcinoma: A case report.

Lyme disease, caused by Borrelia burgdorferi, can produce head and neck manifestations in up to 75% of cases, most commonly facial palsy and lymphadenopathy. Borrelial lymphoid proliferations are recognized mimics of malignancy; however, tonsillar involvement simulating a malignant neoplasm has not been previously described. We report a 57-year-old male patient who presented with a right cervical lump associated with odynophagia, weight loss, and low-grade fever. PET-CT demonstrated intense FDG uptake in a right palatine tonsillar mass and right cervical lymph nodes, with loss of fat plane definition relative to the adjacent sternocleidomastoid muscle. Subsequent MRI revealed an irregular tonsillar mass with restricted diffusion and heterogeneous post-contrast enhancement of the cervical lymph node conglomerate, with internal areas of necrosis, imaging features highly suspicious for oropharyngeal squamous cell carcinoma with extranodal extension. Histopathological examination of the cervical lymph nodes revealed reactive lymphadenitis, and serological testing detected IgM for Borrelia burgdorferi. The patient was treated with doxycycline and demonstrated significant reduction of the tonsillar mass and cervical lymph nodes at three-month follow-up imaging. This case illustrates that infectious etiologies, even rare ones, can produce imaging findings that closely mimic carcinoma, and reinforces the importance of clinical correlation and imaging follow-up before committing to aggressive treatment.