Chapter X 



HISTAMINE IN TISSUE MAST CELLS: MAST CELLS, HISTAMINE 

 AND HEPARIN IN PATHOLOGICAL CONDITIONS 



IN view of the apparently close association between the mast cells and 

 histamine in normal tissues, it seemed desirable next to examine certain 

 pathological tissues in which the mast cells are increased in number. Two 

 such conditions are known: urticaria pigmentosa in man, and mast-cell tumours 

 in domestic animals. Both conditions are rare. 



Urticaria pigmentosa 



Urticaria pigmentosa was first described clinically by Nettleship in 1869 

 (the French still retain the term 'maladie de Nettleship') and later by Thin 

 (1877). Typically it occurs in infants in whom, after periods of exacerbation 

 and remission, the condition usually clears up spontaneously. Two types of 

 urticaria pigmentosa are described: the common one is a generalized rash of 

 copper-coloured spots which when traumatized undergo 'urtication', that is, 

 they resemble the stings of the common nettle, 'urtica urens'. In the other 

 type, which is distinctly rare, the disease shows itself as a solitary lesion, often 

 of considerable size. The pathological basis of both types of lesion is a smaller 

 or greater aggregation of tissue mast cells under a thin epidermis, the basal 

 cells of which are pigmented (Unna, 1896). 



Thanks to the kindness of my former co-worker, Dr. J. M. Drennan, four 

 weighed biopsy specimens in trichloracetic acid were obtained from children 

 with urticaria pigmentosa: two were from cases of the common, generalized 

 type and two from larger solitary lesions. The histological findings in these 

 cases have been described in detail (Drennan, 1951 ; Drennan and Beare, 1954). 

 More recently a further specimen from a case of 'bullous' urticaria pigmentosa 

 (i.e. with lesions progressing to blister formation on trauma) has been obtained 

 from Dr. Girdwood-Ferguson, Glasgow, and another example of the more 

 typical generalized type, arising in an adult patient, from Dr. J. C. Ford, 

 Birmingham (Figs. 24-26). 



So far as the mast-cell content of these specimens is concerned, it suffices to 

 note that in the first of the two solitary lesions the mast cells extended so deeply 

 as to occupy the entire thickness of the biopsy specimen; in the second the mast 

 cells petered out about half way down the tissue block: in contrast, the mast 

 cells were disposed in only a thin layer under the epidermis in the biopsy 

 specimens from the cases with generalized urticaria pigmentosa. By way of 

 controls, histamine was estimated in a sample of skin immediately adjacent 



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