Lipomatosis and focal segmental glomerulosclerosis: causation, association or coincidence?

Sir, Lipomatosis is an extremely rare disorder [1]. Affected persons develop multiple symmetrical, diffuse deposits of fat in the subcutaneous tissue. The lipomata cause physical disfigurement, without tendency to malignancy [1]. Little is known about secondary co-morbidity, with no previous reports of associated renal disease. We describe three patients with lipomatosis who developed biopsy-proven focal segmental glomerulosclerosis (FSGS). A 41-year-old man with lipomatosis since age 18 was incidentally found to have proteinuria (1.36 g/day). Blood pressure and lipid levels were normal. Serum creatinine was 132 mmol/l. Renal biopsy showed FSGS. Prednisone and ramipril led to mild proteinuria reduction. After 110 months, creatinine was 154 mmol/l and proteinuria was 1.92 g/day. Patient 2 developed proteinuria and anasarca at age 7. These rapidly resolved with prednisone and diuretics. There was no follow-up. Lipomatosis appeared at 25. Urinalysis and blood pressure at 32 were normal. Asymptomatic proteinuria (0.79 g/day) was again noted at 34. Blood pressure, kidney function and albumin remained normal. Renal biopsy showed FSGS. Enalapril led to modest proteinuria reduction. After 134 months, creatinine was 190 mmol/l with proteinuria of 0.79 g/day. The third patient also had undiagnosed childhood renal disease, with peripheral oedema and proteinuria. Symptoms and proteinuria were resolved with herbs. Lipomatosis became apparent at 20. Asymptomatic proteinuria (2.2 g/day) was again noted at 37. Blood pressure was 120/80, serum creatinine was 136 mmol/l and albumin was normal. Renal biopsy showed FSGS. There was minimal response to prednisone, but with subsequent ramipril, proteinuria fell to 0.53 g/day. After 86 months, creatinine had risen to 280 mmol/l with proteinuria of 2.94 g/day. The slow deterioration in all patients occurred despite ACE inhibitor therapy and optimal blood pressure and lipid control. FSGS is a common renal diagnosis, with non-specific histological findings. Of interest here is the unifying association with lipomatosis. FSGS can be primary or secondary. Clinical and biopsy features usually allow distinction. In our patients, the lack of symptoms, degree of proteinuria, electron microscopic findings and slow progression suggested secondary disease. In patient 1, we were unable to identify any coexisting disorders associated with secondary FSGS. The other two patients had undiagnosed childhood renal disease, which, despite apparent resolution with therapy, may have been predisposing. Regardless, the rarity of lipomatosis makes the chance of finding the same renal lesion in the three patients less likely. Further, the same renal lesion occurs in obesity, a condition also associated with adipocyte excess. The mechanism underlying this association remains unclear, but the effects of adipocyte-derived hormones on glomerular structure and function have been suggested, with leptin, TNF-α and angiotensin II being identified as potential mediators [2,3]. We suggest a possible link between adipocyte tumour cell hormone production and the development and/or progression of FSGS in our patients. Increased reporting of similar cases is needed to confirm this association. Conflict of interest statement. None declared.

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