In 1957 Rich [1] presented observations in 20 children with the nephrotic syndrome who died between several months and five years after the onset of edema. One-half of these children died from infection. He described a progressive sclerosis of glomeruli starting in the juxtamedullary region of the kidney and suggested that this was the usual way in which lipoid nephrosis progressed. A few years later, studies of renal biopsy specimens from patients with the idiopathic nephrotic syndrome revealed a particular group that was characterized by the presence of focal sclerosing glomerular lesions as distinct from others with minimal or diffuse glomerular lesions [2–4]. It is only in recent years that a clear correlation has been established between these focal lesions and a specific clinical course. A high incidence of microscopic hematuria, corticosteroid resistance and developing renal insufficiency in nephrotic patients with this finding has now been reported by most authors [5–17].

Since the lesions under discussion are characterized by focal involvement of glomeruli and by the sclerotic changes which take place in affected glomeruli, the terms focal glomerular sclerosis (FGS) or focal sclerosing glomerulonephropathy [17] seem appropriate. Other names such as focal sclerosing glomerulonephritis [4, 16] or focal glomerulosclerosis [11, 15, 20] have been proposed. In our opinion the word ‘glomerulonephritis’ should be avoided because of the confusion it may introduce in reference to focal and segmental glomerulonephritis [9]. The term ‘focal gbmerulosclerosis’ is also confusing since, for decades, the word ‘glomerulosclerosis’ has been used for the small sclerotic glomeruli often found in infant kidneys [18, 19].

The frequent histologic finding of FGS in nephrotic patients whose clinical presentation at onset could not be distinguished from that of ‘nephrosis,’ or who might have exhibited minimal glomerular lesions on a previous biopsy specimen [3, 5, 8, 13, 14, 16, 17], raises an important question as to the relationship between ‘minimal lesion nephrotic syndrome’ (M LNS) and this ‘disease’ (FGS). A recent report of the possible recurrence of the nephrotic syndrome and the focal lesion in transplanted kidneys suggests that a humoral factor may be operative which antedates the glomerular structural changes. Accurate diagnosis of FGS in nephrotic patients may therefore be of considerable practical importance.