Mucinous Tubular and Spindle Cell Carcinoma (MTSC)

Epidemiology and Etiology:

• Wide age range (mean 53 y.)
• F > M (4:1)

Common sites:

Gross features:

• Well-circumscribed
• Grey or light tan, uniform cut surface

Histologic features:

• Low-grade
• Mucinous tubular features
• Tightly packed, small, elongated, parallel tubules
• Separated by pale mucinous stroma
• Spindle cell features
• Parallel tubular arrays often have a spindle cell configuration
• Leiomyoma-like or sarcoma-like
• Small cells
• Cuboidal or oval shapes
• Low-grade nuclei
• Necrosis occasionally
• Foam cell deposits maybe
• Chronic inflammation maybe

Immunophenotype:

Marker:	Sensitivity:	Specificity:
Acid mucin stains (mucinous stroma)
Keratins: LMWK (CAM 5.2, MAK 6) CK7, CK18, CK19 34BE12
EMA	Commonly
Vimentin	Maybe
CD15	Maybe
CD10, villin (neg) (proximal nephron markers)	Generally
Ulex europaeus, Peanut and soya bean agglutinins (extensively +)

• Complex immunophenotype

Molecular features:

• Characteristic pattern of chromosome losses and gains:
• Losses:
• 1,4,6,8,13,14
• Gains:
• 7, 11, 16, 17

Other features:

• Asymptomatic usually, incidental U/S finding
• In past may have been diagnosed as unclassified or spindle cell (sarcomatoid) carcinoma
• EM: epithelial features (tight junctions, desmosomes, microvillous borders, luminal borders, occasional tonofilaments)
• Favourable prognosis (limited data – only one metastasis reported)

References:

• Eble JN, Sauter G, Epstein JI, Sesterhenn IA. (eds.) WHO Pathology & Genetics: Tumours of the Urinary System and Male Genital Organs (2004)