Giant Pilomatrixoma of the Cheek Mimicking Malignancy in an Adult With Concurrent Lymphadenopathy: A Case Report and Review of the Literature

Pilomatrixoma is a benign adnexal tumor of hair-matrix origin that typically presents as a small nodule in childhood.We present a 45-year-old male with a left cheek mass, first noted in July 2025, that enlarged rapidly over approximately three weeks from the size of a grape to the size of a baseball, measuring more than 5 cm on computed tomography (CT), with ulceration, serous drainage, and bleeding.He had a 20-year history of smokeless tobacco use and a biopsy-negative, corticosteroid-responsive episode of mediastinal lymphadenopathy more than five years earlier.Contrast-enhanced CT and whole-body 18Ffluorodeoxyglucose (FDG) positron emission tomography-CT (PET-CT) showed an intensely hypermetabolic exophytic facial mass with cervical, mediastinal, and bilateral hilar hypermetabolic lymphadenopathy, raising concern for lymphoma or metastatic carcinoma.Core-needle biopsy of a left cervical lymph node showed reactive lymphadenitis with scattered eosinophils, and punch biopsy of the overlying skin showed a chronic granulomatous and foreign-body giant-cell reaction.Excision confirmed a ruptured pilomatrixoma with an exuberant foreign-body reaction, tumor-free margins, and no evidence of malignancy.Ruptureassociated granulomatous inflammation is the most plausible explanation for the lesion's FDG avidity.The mediastinal and hilar lymphadenopathy, which predated the facial mass, was not further characterized and is best regarded as a separate, unresolved process.In this patient, FDG avidity and concurrent lymphadenopathy produced a convincing picture of malignancy that was resolved only by tissue diagnosis of the primary lesion.