During the past decades numerous attempts to make a reasonable classification of the diseases manifesting themselves as nodules of the legs have been made, but none of the classifications has been generally accepted.
The development of the immunohistological method as a diagnostic aid has shed more light on the pathogenesis of these diseases. Yet, the results have been very confusing, not in the least owing to the different clinical and histological diagnostic criteria used.
This study is an effort to compare both histological and immunohistological findings with clinical data compiled on nodular diseases of the legs.
Twenty four patients who gave a clinical impression of erythema nodosum and/or erythema induratum and 10 patients who have been diagnosed as erythema nodosum leprosum were included in this study. Without any prior knowledge of the clinical data and histological diagnosis, the patterns of immunological reaction were studied by avidin biotin peroxidase complex(A B C) method of immunoperoxidase technique and were divided into five groups.
These results were compared with the histological diagnosis and the clinical data.
The results are as follows:
1. Histological diagnosis showed that out of 24 subjects, there were 10 cases of erythema nodosum. None of these cases revealed deposits of immunoglobulins(G, A and M), Cs and fibrin in and around the dermal blood vessels.
2. Histologically 14 among 24 subjects Nvere diagnosed as erythema induratum. In 11 of the 14 cases, immunoglobulins were found in the blood vessels and the fat tissue around the vessels. Cs was positive in 2 cases and fibrin in 9 cases.
3. All 10 cases of erythema nodosum leprosum, revealed deposit of immunoglobulins in and around the dermal blood vessels. Seven cases showed deposit of immunoglobulins in the dermo-epidermal junction, endothelium of dermal blood vessels and inflammatory cells
around the vessels and the appendages. C3 was found in 4 cases and fibrin in 5 cases.
4. In a comparison between 5 cases of tuberculous type and 9 cases of non-tuberculous type of erythema induratum there were no differences in the histological findings and patterns of immunogloblin deposits.
These results suggest that the pathomechanism of erythema induratum and erythema nodsum leprosum in this study represents the Arthus reaction, but not of erythema ncdosum. The histological criteria used in this study corresponded well with the immunohis-
tological findings.
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