SARCOIDOSIS 



suspension of typical sarcoid tissue obtained at biopsy. In 

 a positive test a slowly appearing nodule develops over two 

 to four weeks ; in the fully developed form it is reddish purple 

 in colour, raised and firm and 7 or 8 mm. in diameter. 

 According to Seltzbach and Ehrlich (1954), an essential part 

 of the test is to make a biopsy of the nodule at four weeks and 

 establish that its histology is typical of a sarcoid nodule. If 

 this is done they believe that the difficulty arising from non- 

 specific reactions is readily overcome. Control extracts from 

 normal lymph nodes are inert. 



The other relevant finding, so far unconfirmed, is due to 

 Nethercott and Strawbridge (1956). They found in sarcoid 

 material free of tubercle bacilli amounts of mycolic and 

 diaminopimelic acids which provided presumptive evidence 

 of past or present infection with acid-fast bacilli. In Smellie 

 and Hoyle's series there was a history of contact with cases 

 of tuberculosis, sometimes close, in 48 % of cases, which seems 

 too high to be wholly coincidental. Scadding (1956) has 

 described several cases of proved tuberculosis with negative 

 Mantoux reaction in which the lesions were of an indolent 

 nature closely resembling sarcoid. He believes that no real 

 dividing line can be drawn between these cases and those 

 diagnosed as typical sarcoidosis. 



In addition to the hypothesis of anergic tuberculosis, other 

 aetiological suggestions have been that the condition is a virus 

 disease analogous to lymphogranuloma inguinale (cf. the 

 Frei and Kveim tests) or that there is a manifestation 

 of hypersensitivity. From the point of view of the clonal 

 approach to mesenchymal cell reactions, the Kveim reaction 

 probably provides the major clue. This suggests that there is 

 deposited in the dermis non-diffusible material which has 

 determinants specifically related to some clones of cells within 

 the body. When representatives of these clones reach the site, 

 they settle and slowly proliferate, eventually building up 

 the typical sarcoid nodule. The various lesions elsewhere in 

 the body which arise during the course of the disease must be 



II 161 BC 



