The marked resemblance between the histological picture of granuloma annulare and that of the rheumatic nodule was first noted by Goodman and Ketron in 1936. While a similar histological appearance does not necessarily mean a similar etiology, and there is little to suggest any relationship between granuloma annulare and rheumatoid conditions; nevertheless, it is at least worth exploring the possibility of some common factor being present. In a recent discussion on the rheumatoid serum factor, Kellgren and Ball (1959) examined a series of patients with subcutaneous nodules and found the sheep cell agglutination test (S.C.A.T.) positive in 100% of 62 males and 92% of 91 females. It seems probable that the rheumatoid serum factor is in some way connected with the subcutaneous nodules, and if these are in any way related to granuloma annulare one might expect this latter condition to be associated with a positive S.C.A.T. The first patient
HELLIER FF. The Sheep Cell Agglutination Test in Granuloma Annulare. Arch Dermatol. 1960;82(2):265. doi:10.1001/archderm.1960.01580020107025
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