PMC6872857_01
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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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).
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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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).
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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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).
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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The postauricular mass was resected in continuity with fibrofatty tissue from the posterior triangle (Fig. 5).