Histopathology of cutaneous changes in drug-induced coma.

Present knowledge of the histopathology of cutaneous changes seen in drug-induced coma is very incomplete: Only 1 of the 11 papers on this subject mentions follicular or sebaceous gland damage, with very little attention focused on vascular changes. We made a careful study of serial sections from eight cutaneous biopsy specimens from seven patients who suffered drug-induced coma with the following findings: (a) The secretory portion of the eccrine sweat coil is the epithelium most susceptible to necrosis. It is followed by, ex aequo, eccrine sweat duct, hair follicle, and sebaceous gland, and, lastly, the epidermis. (b) In the eccrine sweat duct, the outer root sheath of the hair follicle, and the epidermis, necrosis does not usually appear first in the outermost (basal cell) layer. (c) Necrosis of the outer root sheath of the telogen "club" follicle is usually more advanced than that of the secondary hair germ, and, at times, a spared anagen bulb can be seen in closest proximity. (d) Vascular changes correlate proportionately with epidermal damage and consist of a largely neutrophilic inflammatory infiltrate and blood vessel wall damage, mainly involving arterioles. Our findings contradict the widely accepted hypothesis that pressure is the main cause of the cutaneous changes in drug-induced coma.