Unclassified renal cell carcinoma

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Unclassified renal cell carcinoma
Diagnosis in short

Unclassified renal cell carcinoma with thyroid-like and clear cell-like areas. H&E stain.

LM One of the following: (1) a combination of other RCC histologic types, (2) "non-identifiable" pattern/unrecognizable cell type (3) pure sarcomatoid RCC without an identifiable (epithelioid) RCC subtype
LM DDx clear cell renal cell carcinoma, collecting duct carcinoma, undifferentiated carcinoma extending into kidney, kidney metastasis, retroperitoneal sarcoma, newly described renal tumour or emerging entity - see Vancouver classification, collision tumour
Gross kidney mass
Grossing notes partial nephrectomy grossing, total nephrectomy for tumour grossing
Staging kidney cancer staging
Site kidney - see kidney tumours

Prevalence uncommon
Prognosis poor
Clin. DDx other renal tumours
Treatment excision if feasible

Unclassified renal cell carcinoma, abbreviated URCC, is a malignant epithelial tumour arising from the kidney parenchyma, i.e. a renal cell carcinoma, that cannot be further classified.

General

  • Uncommon.
  • A WHO classification diagnosis of exclusion.
  • Worse prognosis than clear cell renal cell carcinoma.[1]
  • High variation in the prevalence (when comparing institutions); this suggests a lack of uniformity in the diagnosis of this subtype.[1]

Gross

  • Mass lesion arising from the kidney - solid and/or cystic.
    • Confined to kidney or predominantly within the kidney.

Microscopic

Features:

  • Malignant tumour that is one of the following:[2][3]
    1. A combination of other RCC histologic types (~35% of cases of URCC).
    2. Has a "non-identifiable" pattern/unrecognizable cell type (~60% of cases of URCC).
    3. Pure sarcomatoid RCC without an identifiable (epithelioid) RCC subtype (~5% of cases of URCC).[3]

DDx:

Images

Case 1

Case 2

IHC

  • Pankeratin +ve.
  • PAX8 +ve.
  • Vimentin +ve/-ve.
  • p63 -ve.[4]
    • Usually +ve in UCC.

See also

References

  1. 1.0 1.1 Karakiewicz, PI.; Hutterer, GC.; Trinh, QD.; Pantuck, AJ.; Klatte, T.; Lam, JS.; Guille, F.; de La Taille, A. et al. (Oct 2007). "Unclassified renal cell carcinoma: an analysis of 85 cases.". BJU Int 100 (4): 802-8. doi:10.1111/j.1464-410X.2007.07148.x. PMID 17822461.
  2. Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 293. ISBN 978-0781765275.
  3. 3.0 3.1 Lopez-Beltran, A.; Kirkali, Z.; Montironi, R.; Blanca, A.; Algaba, F.; Scarpelli, M.; Yorukoglu, K.; Hartmann, A. et al. (Sep 2012). "Unclassified renal cell carcinoma: a report of 56 cases.". BJU Int 110 (6): 786-93. doi:10.1111/j.1464-410X.2012.10934.x. PMID 22404824.
  4. Carvalho, JC.; Thomas, DG.; McHugh, JB.; Shah, RB.; Kunju, LP. (Mar 2012). "p63, CK7, PAX8 and INI-1: an optimal immunohistochemical panel to distinguish poorly differentiated urothelial cell carcinoma from high-grade tumours of the renal collecting system.". Histopathology 60 (4): 597-608. doi:10.1111/j.1365-2559.2011.04093.x. PMID 22260386.