Tip lesion variant of primary focal and segmental glomerulosclerosis: clinicopathological analysis of 20 cases

The glomerular tip lesion (GTL) is a distinctive histopathologic lesion which is regarded as a variant of focal and segmental glomerulosclerosis (FSGS). The prognostic significance of GTL among other FSGS variants has been disputed. In order to define the clinical features and outcome of GTL, we retrospectively reviewed the presenting clinical features, laboratory and biopsy findings and surveillance in our cohort of GTL, which consisted of 20 adults with native kidneys (mean age 46 years) with follow-up data ranging from 3 to 137 months. At presentation, mean urine protein, serum albumin and cholesterol levels were 5.17 g/d, 2.6 g/dL and 312.9 mg/dL, respectively, and none had renal insufficiency. Microscopic hematuria was detected in five patients. At biopsy, glomerular segmental lesions consisted of GTL without perihilar or collapsing lesions. GTL was observed in a variable proportion of glomeruli from 2.6% to 100%. Mesangial proliferation was seen in nine cases, at a moderate degree in two and mild in the rest. Three biopsies showed mild, two showed moderate interstitial fibrosis/tubular atrophy. Eleven patients received steroids alone and eight received sequential therapy with steroids and a cytotoxic agent. At a mean follow-up of 40.6 months, 17 patients (85%) achieved complete remission of nephrotic syndrome, 15% had partial remission. Four of 17 suffered from recurrences. No patient progressed to end-stage renal disease. Serum albumin at diagnosis was the only predictor of a recurrence (p = 0.037). Microscopic hematuria correlated with incomplete remission (p = 0.045). Our study demonstrates a clearly favorable prognosis in patients with FSGS-GTL variant.