Kidney tumor
Adult renal cell carcinoma
Mucinous tubular and spindle cell carcinoma

Author: Nicole K. Andeen, M.D.
Editor: Maria Tretiakova, M.D., Ph.D.

Revised: 24 August 2018, last major update June 2017

Copyright: (c) 2003-2018,, Inc.

PubMed Search: Mucinous tubular spindle cell carcinoma kidney

Page views in 2018: 4,311
Page views in 2019 to date: 261
Cite this page: Andeen, N.K. Mucinous tubular and spindle cell carcinoma. website. Accessed January 23rd, 2019.
Definition / general
  • Renal epithelial neoplasm characterized by "tubular formations merging with bland spindle cells and a myxoid stroma" (WHO 2016)
  • Low grade polymorphic renal epithelial neoplasm with variable components of tubular architecture, extracellular basophilic mucinous material and spindle cell areas
  • First described in 2001 - 2002 (Hum Pathol 2001;32:506, Mod Pathol 2002;15:1162); prior cases classified as sarcomatoid papillary renal cell carcinoma or unclassified
Essential features
  • Usually bland renal epithelial neoplasm with tubules merging with bland spindle cells in a myxoid stroma; behavior generally indolent
  • May share immunohistochemical (CK7+, AMACR+) and morphologic features with papillary renal cell carcinoma, but genetically distinct
  • Previously called low grade tubular mucinous renal neoplasm, low grade collecting duct carcinoma, low grade myxoid renal epithelial neoplasm with distal nephron differentiation
  • Accounts for < 1% of all renal neoplasms
  • Median age 58 years (range 13 - 81)
  • Female:male ratio: 4:1 (Diagn Pathol 2015;10:168)
Clinical features
Radiology images

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Various images

Case reports
  • Resection; additional therapy may be indicated
Gross description
    • Well circumscribed, 2 - 10 cm (mean 4 cm)
    • Confined to kidney; grayish white to tan to yellow glistening cut surface; may have focal hemorrhage; no renal vein invasion
Gross images

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Cut surface with focal hemorrhage

Microscopic (histologic) description
  • Long tubular profiles or cord-like growth pattern of uniform, bland, low cuboidal cells with eosinophilic, focally vacuolated cytoplasm which transition to anastomosing spindle cells
  • Stroma is myxoid and bubbly with abundant extracellular mucin; focal clusters of foamy macrophages
  • Well circumscribed with partial surrounding rim of compressed fibrous tissue
  • Some cases may be mucin poor (highlighted by Alcian blue)
  • May have well formed papillae, clear cells, foamy macrophages, necrosis (Am J Surg Pathol 2006;30:1554, Ann Diagn Pathol 2007;11:13) or rarely neuroendocrine differentiation (Am J Clin Pathol 2006;125:99)
  • Rare high grade nuclei and sarcomatoid change have been described
  • Generally no desmoplasia, no inflammation, no infiltrative growth, no hobnail epithelium, no cysts
Microscopic (histologic) images

Images hosted on PathOut server:

Images contributed by Nicole K. Andeen, M.D. and Maria Tretiakova, M.D., Ph.D.

Mucinous tubular and spindle cell carcinoma

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Long cords and
tubules with bland
nuclear features
in myxoid stroma

Areas of spindled growth (Page 17)

Various images

Case with sarcomatoid growth


Myxoid stroma is Alcian blue+

Virtual slides

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53 year old woman

Cytology description
Positive stains
Negative stains
  • RCC Ma (positive in 7%), villin, Ki67 highlights low proliferative rate (< 1%)
Electron microscopy description
  • Moderate amount of mitochontria, rough endoplasmic reticulum, dense core granules and focal microvilli
  • No renin granules or glycogen (Pathol Int 2004;54:201)
Molecular / cytogenetics description
  • Hypodiploid with multiple chromosomal losses (-1, -4, -6, -8, -9, -13, -14, -15, -22), some hypertriploid but no identifiable pattern (Mod Pathol 2006;19:186)
  • No trisomies 7 / 17 or loss of Chr Y
Molecular / cytogenetics images

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CGH (Figure 7) and LOH (Figure 8)

Differential diagnosis
  • Collecting duct carcinoma: high nuclear grade, desmoplasia and infiltrative features; mucinous tubular and spindle cell carcinoma is usually low grade and well circumscribed
  • Metanephric adenoma: lacks spindled cells and mucinous stroma; positive for WT1 and CD57, negative for AMACR and CK7
  • Papillary renal cell carcinoma (PRCC): both papillary renal cell carcinoma and mucinous tubular and spindle cell carcinoma may have papillae, mucin, low grade features, foam cells, AMACR and CK7 expression
    • look for more prominent mucinous tubular and spindle cell carcinoma biphasic features of anastomosing tubules with spindle cells in mucinous stroma
    • PRCC diffusely express CD10 and has classic trisomy 7 / 17 genomic signature (Am J Surg Pathol 2008;32:1353, Mod Pathol 2006;19:488)
  • Sarcomatoid renal cell carcinoma: infiltrative, usually a high degree of nuclear pleomorphism, areas of more typical renal cell carcinoma subtypes
  • Smooth muscle tumor: more distinct fascicular architecture, absence of tubular areas
Board review question #1
If necessary, one reliable feature to distinguish mucinous tubular and spindle cell carcinoma from papillary renal cell carcinoma in a challenging case is:

  1. Clinical and radiographic evaluation
  2. Genomic evaluation
  3. Immunohistochemistry
  4. Morphologic features of papillary growth and foam cells
Board review answer #1
B. The papillary genomic signature of +7, +17 and loss of chromosome Y is not shared with mucinous tubular and spindle cell carcinoma