Calcifying fibrous pseudotumor of the neck: Diagnostic challenges of a rare benign lesion

Neck masses, frequently encountered by physicians, comprise a vast range of diagnoses, with malignancy being the greatest concern. Calcifying fibrous pseudotumor (CFP) is a rare lesion with unknown pathogenesis, characterized pathologically by a predominance of abundant hyalinized collagenous tissue with focal lymphoplasmacytic infiltrate and psammomatous or dystrophic calcifications. We present the case of a 29-year-old woman who presented with a 4-cm left neck mass, accompanied by constitutional symptoms of vague weakness and lethargy. After the lesion failed to respond to a course of antibiotic therapy, fine-needle aspiration was performed, the pathology of which was indeterminate. The concern was that the lesion was a lymphoproliferative disorder - further workup was performed. CT of the chest, abdomen, and pelvis revealed no evidence of adenopathy or neoplasms. Subsequently, an incisional biopsy was performed, suggesting a diagnosis of CFP. Magnetic resonance imaging with contrast, performed to delineate the anatomy, revealed the lesion in the left neck, deep to the left clavicle, that extended superiorly into the supraclavicular fossa. Complete surgical removal of the lesion was successfully performed, with immunophenotyping confirming the initial diagnosis of CFP. We present a case report of cervical CFP, discuss the approach to neck masses, and review the recent literature on this rare, benign entity.