PG Corner- Case 17

Dr Anuj ParkashWritten by | HISTOPATHOLOGY, PG CORNER

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50 year old male with incidental detection of mass in right kidney on ultrasound. Partial nephrectomy done thereafter.

Gross specimen

Fig. 17a; Gross: Well circumscribed tumor with mahogany brown cut surface and central scar


Fig 17b; H&E; 20x

Fig 17c; H&E; 20x

Click here to reveal the microscopic description


Fig 17d; CK7

Fig 17e; AMACR

Fig 17f; CD117

Fig 17g; SDHB

Fig 17h; E-Cadherin

Click here to reveal the IHC findings

Questions & Answers:

  1. What is your diagnosis?
    • Oncocytoma
    • Chromophobe Renal Cell Carcinoma
    • Succinate Dehydrogenase deficient RCC
    • Low grade Oncocytic tumor
  2. Which of the following is true for above tumor?
    • Strong CK7 and AMACR positivity
    • Subset of cases are CD117 negative
    • Positive for Hale colloidal iron staining
    • Negative for Low molecular weight cytokeratin
  3. Hybrid case of Oncocytic tumor and Chromophobe RCC is seen in:
    • Birt-Hogg-Dube Syndrome
    • Tuberous Sclerosis
    • VHL syndrome
    • MIT Family translocation RCC

Click here to reveal the answers

  • Oncocytoma is a benign epithelial tumor with solid, solid-nested, or cystic architecture
  • Incidence: Constitute 5-9% of all renal cell neoplasm
  • Age: Peak at 7th decade
  • Clinical findings: Most of the cases are asymptomatic and are detected incidentally on radiological investigations for some other cause
  • Location:
    • Predominantly cortex based
    • Large tumors can expand into medulla, renal sinus and even large renal vein branches
  • Gross features:
    • Cut surface: Mahogany brown to tan or yellow with central scar
  • Microscopic features:
    • Solid- nested architecture is characteristic
    • Rarely small papillary protrusion into renal tubules or in cystic areas
    • Composition of microcyst and macrocyst can occur
    • Some cases can show degenerative changes in the form of bizarre cells with pleomorphic nuclei
  • Immunohistochemistry:
    • Positive stains: CD117, E-cadherin, Pancytokeratin & Low-molecular weight cytokeratin
    • Rarely positive for: CD10 & AMACR
    • Negative stains: CK7, Vimentin (may be positive in small cells around the central scar)
  • Hale colloidal iron staining is negative but can show positivity in luminal aspect of cells
  • Genetic susceptibility:
    • Sometimes can be seen in association with Birt-Hogg-Dube Syndrome: Have hybrid Oncocytic and Chromophobe tumor
  • Differential Diagnosis:
    1. Chromophobe Renal cell carcinoma: Positive for CD117 & CK7, while are negative for Vimentin
    2. Low Grade Oncocytic tumor: Positive for CK7, while are negative for CD117
    3. Succinate dehydrogenase deficient RCC: Negative for CD117 & CK7. SDHB expression is lost

Contributed by: Dr. Meenakshi Kamboj

Compiled by: Dr. Diksha Karki

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Last modified: 08/09/2021

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