Trichilemmal Carcinoma Metastatic to Parotid Gland: First Report of Fine Needle Aspiration Cytology Features

This report documents the first description of fine-needle aspiration cytology (FNAC) features of trichilemmal carcinoma, a rare malignant tumor originating from the hair follicle's outer root sheath. The case involved a trichilemmal carcinoma of the scalp that metastasized to cervical lymph nodes and the parotid gland. FNAC of the parotid lesion revealed tightly cohesive cell clusters with varying cytoplasm amounts, vesicular nuclei, intercellular bridges, keratin masses, and desmoplastic stroma fragments, closely mimicking the tumor's histological features. This enabled the diagnosis of metastasis. The study emphasizes the importance of cytopathologists being aware of these cytological features to avoid misdiagnosis as primary salivary gland carcinoma and ensure accurate diagnosis and management.