A 76‐year‐old man with no significant past medical history presented with a 4‐month history of a rapidly growing left nasojugal mass (Figure, A). Magnetic resonance imaging scan demonstrated a cystic lesion (Figure, B). Surgical excision was performed with findings of a 2 cm subcutaneous lesion (Figure, C), which was enucleated intraoperatively and confirmed as a cyst. Histopathology confirmed a squamous cell carcinoma (SCC) arising from an infundibular cyst (Figure, D). Photomicrographs with haematoxylin and eosin staining — low power photomicrograph (Figure, D1), medium power photomicrograph (Figure, D2), and high power photomicrograph (Figure, D3) — show a squamous epithelium‐lined cyst demonstrating infiltrative growth. The lesion was excised with 0.1 mm margins and the patient underwent radiotherapy after the operation. SCCs arising within pre‐existing cysts are extremely rare and have an unknown transformation mechanism.1 Chronic inflammation, immunosuppression and trauma are recognised risk factors.1 A history of rapid growth and a failure to medically treat a suspected infected cyst should raise suspicion for malignancy.2
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