Four-Cell Population Collision Tumor of the Scalp: A Case Report and Review of Literature

Abstract

Background: Most cases of collision tumors (CTum) usually present with 2 histologic cell types. We report a unique CTum case comprised of 4 cell populations. Additionally, we performed a systematic review of the current literature published on head and neck collision tumors (HNCTum). Methods: Eighty-one-year-old male presents with a scalp lesion of several years’ duration. PET/CT scan demonstrated increased uptake in the scalp. Wide local excision with free flap reconstruction was performed and tissue pathology reviewed. Database search of HNCTum was performed and reported. Results: Specimen histopathology consisted of melanoma, squamous cell carcinoma, basal cell carcinoma, and pleomorphic dermal sarcoma. Thirty-one articles met inclusion criteria: 11 thyroid, 7 cutaneous, 7 laryngeal, 2 lymph nodes, 2 salivary gland, 1 glottic, 1 maxillary sinus, and 1 tonsil. Conclusion: We present a highly unique CTum case of 4 different cell populations. The systematic review provides a comprehensive report of HNCTum in literature.