Renal Neoplasia: Diagnostic Problems and Recently Recognized Entities
Case 6 -
Mucinous Tubular and Spindle Cell Carcinoma
John N Eble, M.D.
Holger Moch, M.D.
53 year old woman. Detection of a renal mass by CT. A
nephrectomy was performed. The patient is free of disease 5 years after nephrectomy. Macroscopic findings: The tumor showed well-circumscribed solid tumor with a
uniform gray cut surface.
Mucinous tubular and spindle cell carcinoma
Mucinous tubular and spindle cell carcinomas are low grade polymorphic renal epithelial neoplasms
with mucinous tubular and spindle cell features. The new WHO classification has included this new tumor
subtype. The tumors usually present as asymptomatic masses, often found on ultrasound. There is a wide
age range from 17 to 82 years and a male to female ratio of 1:4. Macroscopically, mucinous tubular and
spindle cell carcinomas are well circumscribed and have grey or light tan cut surfaces. The tumors are
composed of tightly packed, elongated tubules separated by mucinous stroma. Sometimes, the tumors
simulate leiomyoma or sarcoma. Many of these tumors had been previously diagnosed as unclassified,
sarcomatoid carcinomas or as duct Bellini carcinomas. The tumors have a complex immunophenotype and
stain for cytokeratin and EMA. Markers of proximal nephron such as CD10 are absent. By using
comparative genomic hybridization and fluorescence in situ hybridization, there is a characteristic
combination of chromosome losses, generally involving chromosome 1, 4, 6, 8, 13 and 14. The prognosis
seems to be favorable.
It has been postulated that these tumors are related to the loop of Henle. However, the
immunohistochemical and cytogenetic analysis showed complex immunophenotypes, but could not prove a
derivation from the loop of Henle. There was no genetic relationship to clear cell renal carcinomas.
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