Eosinophilic Renal Tumors Flashcards
WHO/ISUP grading of renal tumors
ISUP 1: Inconspicuous nucleoli at 400x
ISUP 2: (start here for RCC) Conspicuous nucleoli at 400x, but not at 100x
ISUP 3: Conspicuous nucleoli at 100x, but no rhabdoid or sarcomatoid features
ISUP 4: Rhabdoid or sarcomatoid features
Eosinophilic solid and cystic RCC
Caused by mutations in TSC1 or TSC2 (dysregulated mTOR signaling)
Often just solid, despite the name. Composed of large, eosinophilic cells with large and somewhat eccentric nuclei which may be pleomorphic. When cystic, the large cells often hobnail into the lumen. Lightly basophilic cytoplasmic stippling may be present in occasional cells.
IHC: CD10+, CK20+, CK7 variable, CD117 negative, CAIX negative, cathepsin K focally pos
Biphasic hyalinizing psammomatous RCC
“The mesothelioma of the kidney” - associated with mutations in NF2 or BAP1.
One “phase” has larger, slightly paler nuclei and forms tubules, the other phase has smaller, darker nuclei and forms solid nests or stromal clusters. Hyalinization and psammoma bodies are associated with the latter phase.
About 50% have a clinically aggressive course.
IHC: NF2 loss, CK7 + (but often not as diffuse as papillary), CD10+
Low-grade oncocytic tumor
Often solitary renal neoplasm that consists of oncocytes. Perinuclear halos may be present. Has an “archipelago-like” architecture and sharp transitions to edematous areas with scattered individual cells.
Clinically indolent tumors.
IHC: CK7+ (diffuse), CD117 neg (opposite of oncocytoma), GATA3 +
Eosinophilic vacuolated tumor
Associated with MTOR mutations.
Cells have eosinophilic cytoplasm, central to eccentric, round nuclei with prominent nucleoli, occasional multinucleation, and focal pleomorphism/ancient degenerative atypia. Variably sized, abundant, often large cytoplasmic vacuoles
IHC: CD117+ (membranous), CD10 + (patchy), cathepsin K + (patchy), CAIX negative, CK20 negative, CK7 negative
MiT family translocation-associated RCC
(TFE3 or TFEB)
May appear as a “biphasic” nested tumor with both clear cell and eosinophilic populations (front picture), or as a papillary/alveolar growth pattern with hyalinized papillae/septae lined by clear cells (shown).
IHC: TFE3+ or TFEB+, cathepsin K+ (both), CD10+, AMACR+, may express HMB45/MelanA, CK7 variable, CAIX negative
Papillary renal cell carcinoma
One of the most common subtypes. Papillae or tubules lined by cuboidal eosinophilic cells with low grade nuclei (ISUP 1-2). Foamy macrophages within papillae are classic. Must be >1.5 cm, otherwise it is an adenoma.
Molecular: Trisomy 7 and 17, loss of 4.
IHC: CK7 diffusely positive, AMACR +, CAIX negative, CD117 negative
Excellent prognosis.
Oncocytoma
Classic gross morphologic appearance of “mahogany” tumor with a central scar.
Histologically, a well-circumscribed mass composed of compact large, oncoytic epthelial cells.
