Renal hybrid oncocytic/chromophobe tumour

Renal hybrid oncocytic/chromophobe tumour
Diagnosis in short
Hybrid oncocytic/chromophobe tumour of the kidney. H&E stain.
Synonyms	hybrid tumour
LM	features of renal oncocytoma and chromophobe renal cell carcinoma - varies by subtype
Subtypes	as per Hes et al.: (1) collision tumour-type, (2) renal oncocytoma with scattered chromophobe cells-type, (3) large eosinophilic cells with intracytoplasmic vacuoles-type
LM DDx	renal oncocytoma, chromophobe renal cell carcinoma, renal cell carcinoma, unclassified, SDH-deficient renal cell carcinoma, other renal tumours with eosinophilic cytoplasm
Stains	Hale's colloidal iron +ve
IHC	CD117 +ve, CK7 +ve (variable)
Molecular	no features of ChRCC
Grossing notes	partial nephrectomy grossing, total nephrectomy for tumour grossing
Site	kidney - see kidney tumours
Syndromes	Birt–Hogg–Dubé syndrome
Clinical history	renal mass
Prevalence	very rare
Prognosis	good on very limited data
Treatment	surgical excision

Renal hybrid oncocytic/chromophobe tumour, also hybrid oncocytic/chromophobe tumour (abbreviated HOCT) and hybrid tumour, is a rare kidney tumour with features of chromophobe renal cell carcinoma and renal oncocytoma.

General

• Rare.
• Molecular heterogeneous group - may represent several different entities.
• Prognosis good - based on one series of 11 cases.

May be seen in several contexts:

• Sporadic.
• Birt–Hogg–Dubé syndrome.
• Renal oncocytosis.

Microscopic

Three morphologic patterns as per Hes et al.:

1. Renal oncocytoma and chromophobe renal cell carcinoma collision tumour.
   • Different fields viewed in isolation would be compatible with the different diagnoses. Tumour component do not intermingle.
2. Renal oncocytoma with scattered chromophobe cells.
3. Large eosinophilic cell with intracytoplasmic vacuoles.
   • Prominent nucleoli (ISUP nucleolar grade 3).
   • Perinuclear halos (occasional).
   • Nested architecture.

DDx:

• Renal oncocytoma - may have limited chromophobe-like areas (<=5% of tumour).
• Chromophobe renal cell carcinoma, eosinophilic variant.
• SDH-deficient renal cell carcinoma - lower nuclear grade, not nested.
• Eosinophilic vacuolated tumour (evolving entity).
• Other renal tumours with eosinophilic cytoplasm.
• Renal cell carcinoma, unclassified.

Images

Case 1

• 

  HOCT - low mag. (WC)

• 

  HOCT - intermed. mag. (WC)

• 

  HOCT - high mag. (WC)

Case 2

• 

  HOCT - intermed. mag. (WC)

• 

  HOCT - high mag. (WC)

• 

  HOCT - very high mag. (WC)

• 

  HOCT - intermed. mag. (WC)

• 

  HOCT - high mag. (WC)

• 

  HOCT - very high mag. (WC)

Stains

Features:

• Hale's colloidal iron +ve (apical pattern).

IHC

Features:

• CD117 +ve (practically definitional).
• CK7 +ve - often variable/patchy (oncocytoma-like).

Others:

• Vimentin -ve.
• EMA +ve.
• CD10 +ve.
• PAX8 +ve.

Molecular

• No features characteristic of chromophobe RCC on array-CGH analysis.

Sign out

Left Kidney, Partial Nephrectomy:
- Renal tumour with eosinophilic cytoplasm of undetermined malignant potential 
  in keeping with the so called "hybrid oncocytic/chromophobe tumour", see comment. 
-- Resection margins clear.
-- Tumour limited to kidney.

Comment:
The tumour may be seen in the context of Birt–Hogg–Dubé syndrome.

See also

• Renal tumours with eosinophilic cytoplasm.
• Renal oncocytoma.
• High-grade oncocytic renal tumour.