Multicystic dysplastic kidney and Kallmann's syndrome: a new association?

Background. Kallmann's syndrome is characterized by anosmia and hypogonadot rophic hypogonadism. Radiographic studies of teenagers and older subjects w ith the X-linked form of the syndrome have shown that up to 40% have an abs ent kidney unilaterally. Although this has been attributed to renal 'agenes is', a condition in which the kidney fails to form, little is known about t he appearance of the developing urinary tract either pre- or post-natally i n individuals with Kallmann's syndrome. Methods. We describe two brothers who had features of Kallmann's syndrome. most probably of the X-linked variety, who both had a major urinary-tract m alformation detected before birth. Results. The brothers were found to have unilateral multicystic dysplastic kidneys on routine antenatal ultrasound scanning and both underwent surgica l nephrectomy of these organs post-natally. Immunohistochemical studies on the younger sibling revealed hyperproliferative dysplastic kidney tubules w hich overexpressed PAX2, a potentially oncogenic transcription factor, and BCL2, a cell-survival factor, surrounded by metaplastic, alpha smooth-muscl e actin-positive stroma: similar patterns have been observed in patients wi th non-syndromic multicystic dysplastic kidneys. Conclusions, Our results describe a new type of urinary-tract malformation associated with Kallmann's syndrome. However, since multicystic kidneys ten d to involute, only when more Kallmann's syndrome patients are screened in utero or in early childhood using structural renal scans, will it be possib le to establish whether multicystic kidney disease is a bona-fide part of t he syndrome.