Permanent slide sections of this parotid mucoepidermoid carcinoma (MEC) better demonstrate areas of oncocytic/oncocytoid change. Intermediate cells smaller, more hyperchromatic. Mucous cells scattered throughout.

Note: identification of all 3 cell ‘types’ is not required for a dx of MEC.

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Higher magnification of the original frozen section slides: infiltration with aggressive growth pattern, squamoid/oncocytic nests, foci with mucous cells. Tumor is high-grade.

MAML2 rearrangement detected by FISH.

Frozen-section-Friday

📸 Amazing how the background parotid tissue fills in so nicely on permanent sections (it is the same block! I promise!) Can better appreciate variations in cellularity and patchy hemorrhage that contribute to the gross appearance
📸 chondroid matrix, ducts and myoeps on permanent sections

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📸 frozen section, tumor capsule
📸 frozen section, epithelial cells (ducts) and myoepithelial cells
📸 frozen section, nests of myoepithelial cells in myxochondroid matrix

Dx: pleomorphic adenoma

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Folliculocentric dyskeratotic process w/warty surface keratosis, suprabasal clefting, villous rete & dyskeratotic cells [corps ronds (round) and grains (flat)]

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B: bacteria in the low mag picture. Pt likely has an underlying laryngeal chondronecrosis.

These tyrosine-like crystalloids seem to localize most frequently to the true cord, particularly near the macula flava

PMID: 39177813

Pathologic staging = pT4a related to bone invasion (focally invades into submucosa/mucosa of maxillary sinus, no impact on pathologic stage though).

This particular case is high grade.

📸 tumor necrosis, solid growth, and increased mitotic rate (3 in this high power field alone).
📸 EWSR1 break apart FISH positive

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