RESUMO
BACKGROUND: Unilateral renal cystic disease is a rare condition that shares morphological similarities with multicystic dysplastic kidney, the former often distinguished from the latter on some clinical and histopathological grounds. However serious diagnostic and therapeutic dilemmas set in when there is a considerable overlap in the distinguishing features between these entities. CASE PRESENTATION: A 19-year-old African female presented with a chronic severe debilitating right lower quadrant abdominal pain refractory to analgesics. Biochemical investigations and imaging studies revealed a non-functional polycystic right kidney and no identifiable pelvicalyceal system or ureter but with preserved renal function. The marked overlap in clinical presentation between unilateral renal cystic disease and multicystic dysplastic kidney in this patient necessitated further investigation to pose an appropriate diagnosis. A right nephrectomy was performed and histopathological analysis of the resected kidney done, the results of which were more consistent with unilateral renal cystic disease. The post-operative course was favorable. CONCLUSION: Unilateral renal cystic disease with an ipsilateral non-functional kidney and an atretic pelvicalyceal system is a very rare condition that needs to be distinguished from multicystic dysplastic kidney in order to guide management and set prognosis. A suspicion of either of these diseases therefore warrants a thorough clinical evaluation and the appropriate combination of biochemical and imaging investigations.