Tubulocystic carcinoma of the kidney, Bellini duct carcinoma, low grade collecting duct carcinoma

Definition

It is uncertain whether tubulocystic carcinoma is a distinct entity or a variant of collecting duct carcinoma. They show features of the proximal convoluted tubule and distal nephron.

Epidemiology

Tubulocystic carcinoma is a rare neoplasm of adult (mean age 54 years, range 34 to 74 years2) with a strong male predominance1,2. The lesion may be solitary or multiple. Patients often have papillary carcinoma is separate nodules.

Clinical features

This tumour may present with abdominal distention, pain or haematuria.

Macroscopic appearances

The tumours are circumscribed. There are multilocular cysts filled with clear fluid, giving a spongy or "bubble wrap" appearance..

Histopathology

There are tightly packed tubules and intermediate sized cysts. Occasional larger cysts up to 1 cm may be  seen.  The lining cells are cuboidal or flat, some hobnailed, with eosinophilic cytoplasm, forming a single layer. The cells have enlarged irregular nuclei with fine chromatin and prominent nucleoli, corresponding to Fuhrman grade 3. There may be patchy clear cell change.  Papillary structures are rare.  The cysts are closely spaced with a variably fibrotic stroma.  Solid sheets and papillae are lacking.  There is no necrosis or and mitotic activity is low.

Immunohistochemistry

Ultrastructure

There are abundant microvilli forming a brush border, resembling that of the proximal convoluted tubule.  some cell may resemble the intercalated cells of the collecting ducts.

Differential diagnosis

• Benign simple cortical cyst

• Cystic nephroma: female preponderance: cysts are larger and the cells lining the cysts are flattened; nuclei appear benign, lacking nucleoli;

• Multilocular renal cell carcinoma: the locules are lined by clear cells

• Oncocytoma with prominent tubules and cysts: nuclei are regular; cell nests are often solid; stroma is loose and hypocellular

• Mixed epithelial and stromal tumour of the kidney: the stroma is of ovarian type or fibrotic, often forming conspicuous solid areas of tumour

• Multilocular cystic renal cell carcinoma: the cells lining the cysts are flattened with clear cytoplasm; there may be up to a 10% component of solid renal cell carcinoma.

Prognosis

This is a low grade malignancy, some cases developing local recurrences or metastases to lymph nodes, liver or bone.

References

1 Yang XJ, Zhou M, Hes O, et al. Tubulocystic Carcinoma of the Kidney: Clinicopathologic and Molecular Characterization. Am J Surg Pathol 2008; 32:177-187

2 Amin MB, MacLennan GT, Gupta R, Grignon D, Paraf F, Vieillefond A, et al. Tubulocystic carcinoma of the kidney: clinicopathologic analysis of 31 cases of a distinctive rare subtype of renal cell carcinoma. Am J Surg Pathol. 2009 Mar;33(3):384-92.

This page last revised 11.4.2010

©SMUHT/PW Bishop