Preauricular Pilomatricoma Manifesting as an Aggressive Mass

Abstract

Pilomatricoma is an uncommon benign skin tumor arising from the hair follicle. It usually occurs in the head and neck region and is typically found in the pediatric age group particularly girls. The tumor has inconsistent clinical features and may manifest as a small superficial lesion with benign features or a large and seemingly aggressive lesion with local invasion. Due to its variable clinical presentations, it can occasionally be misdiagnosed as a malignant tumor. We encountered a case of pilomatricoma in a 12-year-old girl with a left preauricular swelling for two years, which became progressively larger and more painful in the few weeks before presentation. Clinically, the swelling resembled a malignant parotid tumor. Multiple fine-needle aspirations were performed, but the cytology results were all inconclusive. Subsequent computed tomography scan revealed a well-defined calcified subcutaneous mass with suspicious parotid involvement. The case was posted for tumor excision and superficial parotidectomy. Intraoperatively, however, the mass could be easily separated from the parotid gland. Histopathological examination of the excised specimen showed characteristic ghost cells, basophilic cells, and ossifications typical of pilomatricoma. In conclusion, preauricular pilomatricoma may pose a diagnostic dilemma. A heightened knowledge of the disease is needed for early recognition of its clinical and imaging features to prevent aggressive therapy than is required.

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