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Kidney tumor - adult malignancies

Adult renal cell carcinoma

Mucinous tubular and spindle cell carcinoma

Reviewers: Sean Williamson, M.D. (see Reviewers page)
Revised: 7 November 2014, last major update June 2012
Copyright: (c) 2003-2014, PathologyOutlines.com, Inc.


● Low grade polymorphic renal epithelial neoplasm with variable components of tubular architecture, extracellular mucinous material and spindle cell areas
● Also called low grade tubular-mucinous renal neoplasm, low grade collecting duct carcinoma, low grade myxoid renal epithelial neoplasm with distal nephron differentiation
● First described in 2001-2 (Hum Pathol 2001;32:506, Mod Pathol 2002;15:1162), prior cases were classified as sarcomatoid papillary renal cell carcinoma or unclassified
Epidemiology: primarily women, 32-79 years
Origin: tumor cells apparently have differentiation of distal nephron segments

Clinical description

● Almost always benign behavior with recurrences but very rare distant metastases or death from disease (Histol Histopathol 2008;23:1517, Int J Clin Exp Pathol 2008;1:180)

Case reports

● Cases with sarcomatoid change (Am J Surg Pathol 2009;33:44, Hum Pathol 2008;39:966)
● Unclassified tumor resembling pleomorphic adenoma (Am J Surg Pathol 2007;31:632)
● 63 year old woman (Univ of Oklahoma)
● 67 year old woman (Can Urol Assoc J 2008;2:635)
● Metastasis to liver and lymph node without sarcomatoid change (Hum Pathol 2011;42:444)

Gross description

● Well-circumscribed, 3-10 cm, confined to kidney, often with epicenter in renal medulla; yellow-tan-brown-pink cut surface; may have focal hemorrhage; no renal vein invasion

Gross images

Tan brown cut surface with focal hemorrhage

Micro description

● Well-circumscribed with partial surrounding rim of compressed fibrous tissue
● Long tubular profiles or cordlike growth pattern of uniform, low cuboidal cells with eosinophilic, focally vacuolated cytoplasm and spindling, low grade nuclei
● Stroma is myxoid and bubbly with abundant extracellular mucin; focal clusters of foamy macrophages
● May have limited mucin (highlighted by Alcian blue), well formed papillae, clear cells, necrosis (Am J Surg Pathol 2006;30:1554)
● Rarely neuroendocrine differentiation (Am J Clin Pathol 2006;125:99)
● No desmoplasia, no inflammation, no psammoma bodies, no infiltrative growth, no atypia, no hobnail epithelium, no cysts

Micro images

Circumscribed tumor

Long cords and tubules with bland nuclear features in myxoid stroma

Patient with 3 tumors resected at different times

Areas of spindled growth

Left - extracellular mucin; Right - foamy macrophages

Various images

Case with sarcomatoid growth


Left - Alcian blue+; Right - Hale’s colloidal iron+

Myxoid stroma is Alcian blue+

Peanut agglutinin (PNA)+, EMA+, CK18+, CK19 weakly+

Virtual slides

53 year old woman

Cytology description

● Epithelial tumor with round to oval nuclei associated with strands of metachromatic stromal tissue (Diagn Cytopathol 2007;35:593)
● Report of two cases by FNA (Diagn Cytopathol 2010;38:51)

Positive stains

● EMA (95%), AMACR (93%, Am J Surg Pathol 2006;30:13, Hum Pathol 2006;37:698)
● AE1-AE3, CK7 (81%), CK 8/18, CK19, PAS (highlights basal lamina around tubules), Alcian blue highlights mucin; also neuron specific enolase and either chromogranin or synaptophysin (Histol Histopathol 2006;21:7)
● Occasionally high molecular weight cytokeratin 34betaE12 (15%), vimentin, Ulex or CD10 (15%)

Negative stains

● RCC-Ma (positive in 7%), villin, low proliferative rate (<1%)

Electron microscopy description

● Tubular structures reminiscent of the loop of Henle or distal convoluted tubule

Molecular description

● Multiple chromosomal losses (-1, -4, -6, -8, -9, -13, -14, -15, -22) but no identifiable pattern (Mod Pathol 2006;19:186)

Molecular images

H&E and FISH


Differential diagnosis

Papillary renal cell carcinoma, solid variant (or type 1 / basophilic): may have compact areas of low grade spindle cells lining thin, angulated tubules resembling mucinous tubular and spindle cell carcinoma, but no mucinous stroma, +7, +17 (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

End of Kidney tumor - adult malignancies > Adult renal cell carcinoma > Mucinous tubular and spindle cell carcinoma

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