Track: Case Reports

Topic: Neoplasia,Carcinogensis,Tumor Biology

Abstract:

Pilomatricoma is a common benign cutaneous adnexal neoplasm that originates from hair matrix cells. While diagnosing pilomatricoma from surgical excision specimens is generally straightforward, preoperative diagnosis through fine needle aspiration (FNA) is only successful in approximately 30-40% of cases due to non-specific presentation, imaging limitations, and cytologic findings. The challenge increases when pilomatricoma occurs at an uncommon site or in combination with other complicated conditions, including metastatic malignancies.

A 32-year-old female with a history of locally metastatic papillary thyroid carcinoma presented with hypermetabolic activity in the soft tissues of the right neck (level 3/4) during follow-up. Physical examination revealed a palpable nodule in the right parotid region, prompting subsequent FNA. The smears showed numerous giant cells mixed with calcific debris, and scattered atypical cell groups exhibited cytologic features suggestive of follicular cells. Overall, the findings were suspicious for metastatic papillary thyroid carcinoma.

Subsequent excision of the right parotid gland revealed a well-circumscribed nodulocystic lesion in the lower dermis of the right parotid gland. The histopathological features, including basaloid cells at the periphery, degenerated ghost cells toward the center, central ossifications, and foreign body granulomas with multinucleated giant cells, were consistent with benign pilomatricoma. Multiple lymph nodes from the right neck were positive for metastatic papillary thyroid carcinoma. Given that FNA is an initial non-invasive investigation for diagnosing superficial lesions, including those in the parotid gland, it is crucial to recognize key cytological features and consider the possibility of pilomatricoma even in complicated settings and rare locations alongside metastatic malignancy.

Kristi Adams

Affiliation

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(282) A Cytologic Diagnostic Challenge of Pilomatricoma at the Parotid Gland in the Setting of Metastatic Papillary Thyroid Carcinoma