Is renal medullary carcinoma the seventh nephropathy in sickle cell disease?

A multi-center Nigerian survey.
Madu Anazoeze1, Galadincci Najibah etal.
1. University of Nigeria, Haematology & Immunology; university of Nigeria Teaching Hospital,
Haematology & Immunology
2. Aminu Kano Teaching Hospital, Haematology
3. Federal Medical Center, Haematology
4. Aminu Kano Teaching Hospital, Paediatrics
5. University College Hospital, Ibadan, Department of Haematology
6. Ahmadu Bello University Teaching Hospital, Haematology
7. University of Calabar Teaching Hospital, Calabar, Department of Haematology
8. Ladoke Akintola University of Technology, Haematology
9. University of Nigeria Teaching Hospital, Enugu
10. Nnamdi Azikiwe University, Haematology
11. University of Port Harcourt Teaching Hospital, Nigeria, Department of Haematology
12. University of Benin Teaching Hospital, Haematology

Abstract
Introduction:Previous studies had enlisted renal medullary carcinoma (RMC) as the seventh nephropathy in sickle cell disease  (SCD). Clinical experience has contradicted this claim and this study is targeted at refuting or supporting this assumption.

Objective: To estimate the prevalence of RMC and describe other renal complications in SCD.

Materials and methods: 14 physicians (haematologists and urologists) in 11 tertiary institutions across the country were collated from patients’ case notes and hospital SCD registers.

Results: Of the 3,596 registered sickle patients, 2 (0.056%) had been diagnosed with RMC over a ten year period, thereby giving
an estimated prevalence rate of 5.6 per 100,000. The most common renal complication reported by the attending physicians was
chronic kidney disease (CKD). The frequency of routine renal screening for SCD patients varied widely between centres – most
were done at diagnosis, annually or bi-annually.

Conclusion: The ten year prevalence of RMC in Nigerian SCD patients was determined to be 5.6 (estimated incidence of 0.56).  RMC is not more common in SCD patients and therefore cannot be regarded as a “Seventh Sickle nephropathy”. Most of the  managing physicians reported that the commonest nephropathy observed in their SCD patients was chronic kidney disease.

Keywords: Renal medullary carcinoma, seventh nephropathy, sickle cell disease, Nigerian survey.