PATHOLOGY

Collecting duct carcinoma of the kidney: a clinicopathological study of 9 cases
Peyromaure M, Thiounn N, Scotte F, Vieillefond A, Debre B, Oudard S
Department of Urology, Cochin Hospital, Paris, France
J Urol. 2003; 170: 1138-40

• Purpose: Collecting duct carcinoma (CDC) of the kidney is a rare variant that is associated with an extremely poor prognosis. We report our experience with this variety of cancer in the last 9 years.
• Materials and Methods: From 1993 to 2002, 9 patients with CDC were treated at our institution. The diagnosis of CDC was made by a nephrectomy specimen in 8 cases and by renal biopsy in 1. Tumor characteristics, and patient treatment and outcome are reported.
• Results: At presentation 1 T1N0M0, 1 T3N0M0, 3 T3N+M0 and 4 T3N+M+ tumors were seen. Mean followup was 13.6 months. Five patients received no complementary treatment. The patient with the T1N0M0 tumor remained free of disease 13 months after nephrectomy and the one with T3N0M0 tumor remained free of disease at 17 months. A patient with a T3N+M+ tumor experienced progression at 1 month, local recurrence at 17 months and was then lost to followup. The 2 other patients with T3N+M0 and T3N+M+ disease, respectively, progressed rapidly and were lost to followup after 5 months. One patient with a T3N+M0 neoplasm received immunotherapy and died after 24 months, while the other with T3N+M0 disease was treated with oral prednisolone and died after 5 months. Finally, 2 patients with T3N+M+ disease received chemotherapy, consisting of 1,250 mg/m2 gemcitabine on days 1 and 8, and 70 mg/m2 cisplatin on day 1. Each patient achieved an objective response after 3 chemotherapy cycles and remained disease-free 27 and 9 months after nephrectomy, respectively.
• Conclusions: CDC is an aggressive variety of kidney neoplasm that is often associated with nodal and visceral metastases at presentation. Our data suggest that combined gemcitabine and cisplatin chemotherapy may be the best therapeutic option for patients with this tumor.
  
  
• Editorial Comment
  Collecting duct carcinoma accounts for approximately 1 per cent of renal cell neoplasms. In spite of its rarity is considered one of the most aggressive variants of renal tumors. No consistent pattern of genetic abnormalities has been established. The morphologic features are characterized by irregular tubules reminiscent of the Bellini collecting ducts set in a desmoplastic stroma. An affinity for the Ulex europaeus lectin supports a collecting duct origin for this tumor.
  A differential diagnosis is with renal urothelial carcinoma with glandular differentiation. Favors this latter diagnosis squamous differentiation and dysplastic epithelium or in situ carcinoma in the pelvic urothelium. Another differential diagnosis is the recently described low-grade mucinous and spindle cell carcinoma of the kidney (Mod Pathol. 2002; 15: 182A). Microscopically, it shows tubular structures reminiscent of the thin segment of the loop of Henle. It is a tumor with good prognosis and a striking female preponderance. The immunohistochemistry displays proximal and distal nephronic markers.
  A variant of collecting duct carcinoma is the medullary carcinoma of the kidney. This variant was described by Davis, Mostofi and Sesterhen (Am J Surg Pathol. 1995; 19: 1-11) which is believed to arise from the collecting ducts of the renal medulla and is associated with sickle cell trait. The authors coined this tumor as the seventh sickle cell nephropathy. The other 6 are hematuria, papillary necrosis, nephrotic syndrome, renal infarction, inability to concentrate urine and pyelonephritis.

Dr. Athanase Billis
Full-Professor of Pathology
State University of Campinas, Unicamp
Campinas, São Paulo, Brazil