case_images: PMC6872857_01
case_images: Malignant pilomatrixoma as a firm ovoid mass in postauricular area. The helical defect on the ear is from a previously resected squamous cell carcinoma.
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case_images: He was noted to have a large elliptical mass measuring approximately 4 cm located in the right postauricular area with associated regional lymphadenopathy (Fig. 1).
case_images: Incisional biopsy showing areas composed of nests of basaloid epithelial cells (right) with abrupt keratinization and anucleated ghost cells (left). H&E stain, 4x. These are typical findings in a pilomatrixoma.
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case_images: The incisional biopsy demonstrated a dermal pilomatrixoma (Fig. 2) with cytologic atypia, squamoid differentiation, infiltrative borders, up to 50 mitoses per 10 high-power fields, and atypical mitotic figures (Fig. 3, Fig. 4).
case_images: On high power, the squamoid cells showed marked cytologic atypia with enlarged irregular nuclei, prominent nucleoli, and increased mitotic figures (arrows). H&E stain, 40x.
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case_images: The incisional biopsy demonstrated a dermal pilomatrixoma (Fig. 2) with cytologic atypia, squamoid differentiation, infiltrative borders, up to 50 mitoses per 10 high-power fields, and atypical mitotic figures (Fig. 3, Fig. 4).
case_images: Excised postauricular mass in continuity with fibrofatty tissue from posterior triangle. The mass was tan and firm and measured 4.3 x 3 x 2.2 cm.
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case_images: The postauricular mass was resected in continuity with fibrofatty tissue from the posterior triangle (Fig. 5).