Kidney tumor

Adult renal cell carcinoma - rare

Multilocular cystic renal neoplasm of low malignant potential



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Last staff update: 22 December 2022

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PubMed search: Multilocular cystic renal cell neoplasm of low malignant potential

Maria Tretiakova, M.D., Ph.D.
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Cite this page: Tretiakova M. Multilocular cystic renal neoplasm of low malignant potential. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/kidneytumormcrnlow.html. Accessed January 26th, 2023.
Definition / general
  • Indolent neoplasm composed of low grade clear cells with pure multicystic architecture
Essential features
  • Exclusively cystic, multiloculated renal tumor devoid of any expansile solid growth
  • Clear cells lining with low grade nuclei (WHO / ISUP grade 1 or 2)
  • No progression or metastases when diagnosed on strict criteria
  • Distinguish from regressing clear cell renal cell carcinoma (CCRCC) with cystic degeneration or extensive cystic architecture
  • Diagnosis should not be made in needle biopsy alone because of limited sampling
Terminology
  • Use of multilocular cystic renal cell carcinoma is considered obsolete (WHO 2016); some literature references in this topic use the older terminology
ICD coding
  • ICD-O: 8316/1 - multilocular cystic renal neoplasm of low malignant potential
  • ICD-11: 2F35 & XH7PR9 - benign neoplasm of urinary organs & multilocular cystic renal neoplasm of low malignant potential
Epidemiology
Sites
Pathophysiology
  • Several mechanisms of pathogenesis described:
    • Cyst dependent, VHL associated pathway in which cysts represent a precursor of CCRCC: abnormal microtubule formation and degeneration of primary cilia
    • Tumor arising in a preexisting simple renal cyst
    • Intrinsic cystic growth as unilocular fluid filled mass
    • Intrinsic multilocular cystic growth in proximal convoluted tubules
    • Tumor growth causing obstruction of kidney tubules and cyst formation
    • Cystic regression
  • Most likely represent low grade spectrum in development of CCRCC with ~40% overlapping genes detected both in multilocular cystic renal neoplasm of low malignant potential (MCNLMP) and in cystic CCRCC by next generation sequencing
  • References: Diagn Histopathol 2020;26:320, Virchows Arch 2018;473:85, Annu Rev Pathol 2015;10:263, Investig Clin Urol 2019;60:148
Etiology
Clinical features
Diagnosis
Radiology description
  • Moderately complex, multilocular, cystic
  • Well defined margins
  • Minimal thickening of wall and smooth septa
  • Moderately enhancing fluid equivalent and atypical cysts
  • No intracystic enhancement (J Urol 2017;198:12)
Radiology images

Images hosted on other servers:
Pure multilocular cystic mass

Pure multilocular cystic mass

Prognostic factors
Case reports
Treatment
Gross description
  • Usually unilateral and < 5 cm (mean size: 4 cm)
  • Well circumscribed with fibrous pseudocapsule
  • Variably sized cysts with thin septa
  • Cysts filled with clear, serous, gelatinous or hemorrhagic fluid
  • No mural solid nodules or areas of necrosis
  • Reference: Histol Histopathol 2012;27:969
Gross images

Contributed by Maria Tretiakova, M.D., Ph.D.
Cortical multilocular cystic tumor

Cortical multilocular cystic tumor

Irregular tumor pushing into renal hilum

Irregular tumor pushing into renal hilum

Microscopic (histologic) description
  • Thin, fibrous septa lined by clear cells
  • Low grade nuclei without prominent nucleoli (WHO / ISUP grade 1 - 2)
  • Clear cell clusters may be present within thin septations or fibrous capsule but they should not alter their contours by expansile growth or exceed 1 mm (20x field of view)
  • In rare cases, lining of cysts may show focal multilayering, cells with granular cytoplasm and small intracystic papillations
  • Septa may contain calcification or ossification
  • Presence of necrosis, frequent or atypical mitoses, lymphovascular or fat invasion, rhabdoid or sarcomatoid change are incompatible with diagnosis
  • Reference: Virchows Arch 2018;473:85
Microscopic (histologic) images

Contributed by Maria Tretiakova, M.D., Ph.D. and @ahmsab_MD on Twitter
Variably sized cysts with low grade clear cell lining Variably sized cysts with low grade clear cell lining Variably sized cysts with low grade clear cell lining Variably sized cysts with low grade clear cell lining

Variably sized cysts with low grade clear cell lining


Variably sized cysts with low grade clear cell lining Variably sized cysts with low grade clear cell lining Variably sized cysts with low grade clear cell lining Variably sized cysts with low grade clear cell lining

Variably sized cysts with low grade clear cell lining


Multilocular cystic renal neoplasm of low malignant potential

Multilocular cystic
renal neoplasm
of low malignant
potential
Negative stains
Molecular / cytogenetics description
Sample pathology report
  • Left kidney, partial nephrectomy:
    • Multilocular cystic neoplasm of low malignant potential
    • Tumor size: 3.7 cm
    • Surgical margins: free of tumor
Differential diagnosis
Board review style question #1

What is true about this encapsulated multilocular cystic tumor with clear cell morphology?

  1. Does not require surgical treatment
  2. Frequently progress to conventional clear cell RCC
  3. Necrosis, solid growth and invasion are not allowed for diagnosis
  4. Often associated with acquired cystic kidney disease
  5. VHL mutation or 3p loss are highly unlikely
Board review style answer #1
C. Necrosis, solid growth and invasion are not allowed for diagnosis. Multilocular cystic renal neoplasm of low malignant potential (MCNLMP) has been excluded from the renal cell carcinoma category due to its uniformly good outcomes and has been renamed in the 2016 World Health Organization Classification. Histologically MCNLMP has pure cystic architecture and is composed of clear cells (similar to conventional CCRCC) but these cells are aligned in a single layer and do not form solid expansile nodules or tumor nests. Presence of necrosis, brisk or atypical mitoses, lymphovascular or fat invasion, sarcomatoid or rhabdoid dedifferentiation are incompatible with this diagnostic entity (C). However, despite its indolent behavior, MCNLMP is still treated surgically due to complex cystic morphology by radiologic imaging (Bosniak IIF - IV) (A). Immunostaining and molecular findings are similar to conventional CCRCC; VHL gene alteration due to mutation or 3p loss was documented in the majority of studied cases (E). Because of these similarities, there is a concept that MCNLMP, cystic CCRCC and conventional RCC represent a continuum of pathogenetic development with MCNLMP representing the most indolent end of tumor spectrum; however, no documented cases of actual MCNLMP progression to CCRCC have been reported (B). There is no known association between MCNLMP and acquired cystic kidney disease (D).

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Reference: Multilocular cystic renal neoplasm of low malignant potential
Board review style question #2

What immunohistochemical profile is most consistent with multilocular cystic renal neoplasm of low malignant potential (MCNLMP)?

  1. CAIX+, CK7 variable, CD10+, RCC+
  2. CAIX+, CK7+, HMWCK+, GATA3+
  3. CAIX+, CK7-, TFE3+, vimentin+
  4. CAIX-, TFE3+, cathepsin K+, MelanA+
Board review style answer #2
A. CAIX+, CK7 variable, CD10+, RCC+. Immunostaining is rarely needed for establishing MCNLMP diagnosis, which is primarily based on morphologic assessment; however, if IHC is performed in an MCNLMP case, the expected immunoprofile will be diffuse expression of CAIX and CD10, as well as variable expression of CK7 and RCC (A). Coexpression of CAIX / CK7 plus variable expression of HMWCK and GATA3 are typically seen in clear cell papillary renal cell tumor (B). Conventional clear cell RCC could be distinguished from TFE3 rearranged RCC with panel results C and D, respectively.

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Reference: Multilocular cystic renal neoplasm of low malignant potential
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