Low-grade oncocytic renal tumour

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Low-grade oncocytic renal tumour
Diagnosis in short

Low-grade renal oncocytic tumour. H&E stain.
LM abundant eosinophilic cytoplasm, nuclei uniform and round without significant pleomorphism, solid or tubular architecture
LM DDx renal oncocytoma, chromophobe renal cell carcinoma eosinophilic variant, clear cell renal cell carcinoma eosinophilic variant, papillary renal cell carcinoma oncocytic variant, tubulocystic carcinoma of the kidney, other renal tumours with eosinophilic cytoplasm, benign liver
IHC CK7 +ve, CD117 -ve, PAX8 +ve
Grossing notes partial nephrectomy grossing, total nephrectomy for tumour grossing
Site kidney - see kidney tumours
Clinical history often incidentally discovered mass
Prognosis likely benign
Clin. DDx other kidney tumours

Low-grade oncocytic renal tumour, abbreviated LOT, is an unusual renal tumour that does not neatly fit into any WHO renal neoplasia category. It is also known as renal oncocytic tumour that is CD117 negative and CK7 positive.

Whether it is a distinct entity is not clear as of 2019.[1] It can be considered an emerging entity that may be in the WHO classification of renal neoplasia in the future.[2]

General

  • Very rare.
  • Benign behaviour based on a small series.[1]

Microscopic

Features:[3]

  • Oncocytic cytoplasm.
  • Round nuclei.
  • Tubular or solid architecture.
  • Edematous areas with loosly arranged cells.
  • Low ISUP nucleolar grade - grade 1 or 2.

DDx:

Images

  • LGORT - low mag. (WC)

  • LGORT - intermed. mag. (WC)

  • LGORT - intermed. mag. (WC)

  • LGORT - high mag. (WC)

  • LGORT - high mag. (WC)

  • LGORT - high mag. (WC)

IHC

Features:

  • CK7 +ve.
  • CD117 -ve.

Others:

  • CD10 -ve/+ve.
  • AMACR -ve/+ve.
  • CA9 -ve.
  • CK20 -ve.
  • CD10 -ve.

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Right Kidney Mass, Biopsy:
- Low-grade oncocytic tumour (see comment).

Comment:
The tumour stains as follows:
POSITIVE: CK7 (strong, diffuse), CD117 (very focal), PAX8 (strong, diffuse), AE1/AE3, AMACR, E-cadherin, BerEP4.
NEGATIVE: CD10, CK20, vimentin, CA9.

This tumour does not completely fit the diagnosis of renal oncocytoma or eosinophilic chromophobe renal cell carcinoma. 

It is in keeping with "low-grade oncocytic tumour" (LOT), an evolving entity. Based on limited data, LOT appears to have an indolent behavior.

See also

References

  1. ↑ 1.0 1.1 Trpkov K, Williamson SR, Gao Y, Martinek P, Cheng L, Sangoi AR, Yilmaz A, Wang C, San Miguel Fraile P, Perez Montiel DM, Bulimbasić S, Rogala J, Hes O (August 2019). "Low-grade oncocytic tumour of kidney (CD117-negative, cytokeratin 7-positive): a distinct entity?". Histopathology 75 (2): 174–184. doi:10.1111/his.13865. PMID 30895640.
  2. ↑ Siadat F, Trpkov K (January 2020). "ESC, ALK, HOT and LOT: Three Letter Acronyms of Emerging Renal Entities Knocking on the Door of the WHO Classification". Cancers (Basel) 12 (1). doi:10.3390/cancers12010168. PMC 7017067. PMID 31936678. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7017067/.
  3. ↑ Trpkov K, Williamson S, Martinek P, Cheng L, San Miguel Fraile P, Yilmaz A, Hes O, Oncocytic Renal Tumors with CD117 Negative, Cytokeratin 7 Positive Immunoprofile are Different from Eosinophilic Chromophobe Renal Cell Carcinoma (ChrRCC) and Oncocytoma. United States and Canadian Academy of Pathology Annual Meeting 2018.
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