ALT NUCHAL-TYPE FIBROMA A: Low-power view of a typical nuchal fibroma showing involvement from dermal to subcutaneous tissue by a densely eosinophilic and poorly circumscribed lesion. B: At medium to high power, nuchal fibroma consists of dense, hyalinized collagen with a “cracked earth” appearance and inconspicuous bland nuclei. C: Higher magnification shows the dense collagen, low vascularity, and small fusiform nuclei with no atypia.
ALT LOW-GRADE NASOPHARYNGEAL PAPILLARY ADENOCARCINOMA A–C: Papillary arrangement of crowded, elongated to cuboidal tumor cells mimics papillary thyroid carcinoma. D: There is a loose central fibrovascular core. E: Nuclei are oval and irregular with pale chromatin and occasional grooves. F,G: Some areas of the tumor have a more solid growth pattern (F) consisting of back-to-back glands forming a somewhat cribriform arrangement (G). Some cells are vacuolated.
ALT EMBRYONAL RHABDOMYOSARCOMA A: At low power, this subtype of rhabdomyosarcoma is often concentrated beneath the surface epithelium. B: At high power, the primitive spindled cells with hyperchromatic nuclei are set in a myxoid stroma. Inset: Desmin immunohistochemistry is positive.
ALT GRANULAR CELL TUMOR A: Polygonal cells with granular eosinophilic cytoplasm and uniform nuclei. B: Granular cells are strongly immunoreactive with S-100 protein.
ALT GRANULAR CELL TUMOR A: Pseudoepitheliomatous hyperplasia overlying an unencapsulated granular cell tumor extending into the skeletal muscle. B: High-power view of the pseudoepitheliomatous hyperplasia associated with the granular cells.
