Mucinous tubular and spindle cell carcinoma, loopoma
Definition
A rare type of renal cell carcinoma composed of a combination of low-grade tubular cuboidal cells and spindle cells in a mucinous stroma. It has been suggested that they are reminiscent of, and derived from, the loop on Henle2 or collecting duct4. Previous reports of collecting duct carcinoma may have contained some such tumours6,7.
Epidemiology
This is a very rare type of renal cell carcinoma. It occurs in adults across a wide age range, with an equal sex incidence2. There is an association with nephrolithiasis2.
Macroscopic appearance
The tumours are circumscribed, with a pushing non-infiltrating margin. They have an "elastic" consistency and contain small foci of haemorrhage and necrosis2.
Histopathology
The tumour is composed of two cell types. The predominant type is a spindle cell with sparse cytoplasm, arranged in fascicles, resembling a low-grade smooth muscle tumour. The second is a small cuboidal cell forming tubular structures and sheets. The tubules are elongated and curving, giving a "fingerprint" appearance. There is a bubbly myxoid stroma which stains intensely with alcian blue. In places, cord of cells float in the abundant stroma, reminiscent extraskeletal myxoid chondrosarcoma . Cysts and papillae are not seen. The cytological appearances are low grade. There is scant cytoplasm and nuclei may protruding into lumina to give a hobnail appearance. Mitoses occur, but are rarely atypical.
One reported case was associated with a conventional renal cell carcinoma2.
Immunohistochemistry (with results for papillary renal cell carcinoma for comparison):
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Mucinous tubular and spindle cell carcinoma
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Papillary renal cell carcinoma
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AMACR
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25/27(>50% positive: 21 cases, 11-50% positive: 2 cases, 5-10% positive: 2 cases, < 5% positive: 2 cases. Staining was seen in both tubular and spindle cells)1
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19/20(>50% positive: 14 cases, 11-50% positive: 5 cases, < 5% positive: 1 case)1
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Cam5.2
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4/112, 4/4 (but weak)3
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AE1/AE3
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11/112, 4/43
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CK7
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22/27(>50% positive: 15 cases, 11-50% positive: 4 cases, 5-10% positive: 3 cases, < 5% positive: 5 cases. Staining was seen in both tubular and spindle cells. The tubular cells show strong cytoplasmic staining, like that seen in papillary renal cell carcinoma)1, 9/92, 4/43
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13/20(>50% positive: 10 cases, 11-50% positive: 3 cases, < 5% positive: 7 cases)1
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CK19
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0/43
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CK20
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0/43
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34bE12
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4/26(>50% positive: 1 case, 11-50% positive: 2 cases, 5-10% positive: 1 case, < 5% positive: 22 cases)1, 4/43
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3/20(>50% positive: 2 cases, 11-50% positive: 1 case, < 5% positive: 17 cases)1
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EMA
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19/20(>50% positive: 8 cases, 11-50% positive: 9 cases, 5-10% positive: 2 cases, < 5% positive: 1 case. There was strong membrane and weaker cytoplasmic staining.)1, 11/112, 4/43
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15/17(>50% positive: 9 cases, 11-50% positive: 3 cases, 5-10% positive: 3 cases, < 5% positive: 2 cases)1
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Vimentin
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11/112, 4/43
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RCC Marker
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2/27(>50% positive: 2 cases, < 5% positive: 25 cases)1, negative4
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5/20(>50% positive: 3 cases, 5-10% positive: 2 cases, < 5% positive: 15 cases)1
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CD10
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4/27(>50% positive: 4 cases, < 5% positive: 23 cases. The cases that stained showed membranous staining in the tubular cells and cytoplasmic staining in the spindle cells)1
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16/20(>50% positive: 13 cases, 11-50% positive: 2 cases, 5-10% positive: 1 case, < 5% positive: 4 cases)1
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CD15
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0/112, 0/43
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CD117
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1/21(5-10% positive: 1 case, < 5% positive: 20 cases)1
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3/17(>50% positive: 1 case, 11-50% positive: 1 case, 5-10% positive: 1 case, < 5% positive: 14 cases)1
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Ulex europaeus
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1/4(one case focally positive)3
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S-100
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the spindle cells are negative, 0/92, 0/43
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SMA
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the spindle cells are negative, 0/112
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Desmin
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the spindle cells are negative, 0/112, 0/43
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HMB45
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0/112
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Villin
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negative4
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pCEA
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0/43
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MIB1
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up to 15/HPF2
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kidney-specific cadherin
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0/238
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Ultrastructure
The cuboidal cells have short microvilli on the apical borders and tight junctions on the lateral borders. There are no melanosomes or microfilaments2.
Cytogenetics
There are genetic losses involving multiple chromosomes4,5. Fluorescence in situ hybridization detects no von Hippel-Lindau gene deletions on chromosome 3p25, which are characteristic for clear cell renal carcinomas5. The gains in chromosomes 7 and 17 and loss of chromosome Y characteristic of papillary renal cell carcinoma are not see in mucinous tubular and spindle cell carcinoma.
Differential diagnosis
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Papillary renal cell carcinoma with sarcomatoid change. The tubular cells are similar to those of basophilic papillary renal cell carcinoma and the spindle cell component. However, the spindle cells are polymorphous with prominent nuclei. Mitotic figures, including atypical mitoses, are common. Rarely, papillary renal cell carcinoma may show extracellular mucin. The prognosis is far worse than for mucinous tubular and spindle cell carcinoma.
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Collecting duct carcinoma: also shows the hobnail appearance due to nuclei protruding into lumina. However, they have infiltrating margins and high-grade cytology. They are positive for Ulex europaeus and pCEA.
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Metanephric adenoma: there is a small acinar component whcih has basophilic cytoplasm. These tumours are devoid of stroma and a spindle cell component is lacking. They are always negative for CK7 and EMA.
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Angiomyolipoma with a predominant leiomyomatous component: there is positivity for HMB45 and HMB50. Premelanosomes are present on electron microscopy.
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Smooth muscle neoplasm are positive for SMA, desmin and other muscle markers.
Management
Patients have been treated by simple nephrectomy2.
Prognosis
To date, only two of forty six cases have shown metastases2 and there have been no tumour-related deaths.
References
1 Paner GP, Srigley JR, Radhakrishnan A, et al. Immunohistochemical Analysis of Mucinous Tubular and Spindle Cell Carcinoma and Papillary Renal Cell Carcinoma of the Kidney: Significant Immunophenotypic Overlap Warrants Diagnostic Caution. Am J Surg Pathol 2006; 30:13-19
2 Hes O, Hora M, Perez-Montiel DM, et al. Spindle and cuboidal renal cell carcinoma, a tumour having frequent association with nephrolithiasis: report of 11 cases including a case with hybrid conventional renal cell carcinoma/ spindle and cuboidal renal cell carcinoma components. Histopathology 2002; 41:549-55
3 Parwani AV, Husain AN, Epstein JI, et al. Low-grade myxoid renal epithelial neoplasms with distal nephron differentiation. Hum Pathol 2001; 32:506-12
4 Rakozy C, Schmahl GE, Bogner S, et al. Low-grade tubular-mucinous renal neoplasms: morphologic, immunohistochemical, and genetic features. Mod Pathol 2002; 15:1162-71
5 Weber A, Srigley J,Moch H [Mucinous spindle cell carcinoma of the kidney. A molecular analysis]. Pathologe 2003; 24:453-9
6 MacLennan G, Farrow GM, Bostwick DG: Low-grade collecting duct carcinoma of the kidney: Report of 13 cases of low-grade mucinous tubulocystic renal carcinoma of possible collecting duct origin. Urology 50:679-684, 1997
7 Srigley JR, Eble JN, Grignon DJ, et al: Unusual renal cell carcinoma (RCC) with prominent spindle cell change possibly related to the loop of Henle. Mod Pathol 12:107A, 1999.
8 Kuehn A, Paner GP, Skinnider BF, et al. Expression analysis of kidney-specific cadherin in a wide spectrum of traditional and newly recognized renal epithelial neoplasms: diagnostic and histogenetic implications. Am J Surg Pathol 2007; 31:1528-33
This page last revised 2.2.2008.
©SMUHT/PW Bishop