124 An I nl induction to Medical Mycology 



mycologic examinations (usually repeated several times), the laek of in- 

 volvement of the scalp and the localization to areas not commonly the sites 

 of psoriasis, such as the palms, the soles or the inner surfaces of the thighs, 

 should make one suspicious. The presence of bleeding points after removal 

 of the scale is not usual with the mycotic disorder. The histologic picture 

 usually observed with psoriasis is absent in case of fungous infection. Pru- 

 ritus, if severe, favors the diagnosis of dermatophytosis. 



b. Neurodermatitis (atopic eczema). On close inspection the affected 

 patch will be seen to be lichenified, with exaggerated cutaneous markings. 

 Scratch marks may be noted, as with the fungous disease. Careful investiga- 

 tion of the history will elicit the fact that pruritus and scratching by the 

 patient preceded the rash. There may be a history of allergy to foods or to 

 inhalants or a tendencv to another allergic disorder, such as hay fever 

 or asthma. 



( 4 ) Onychomycosis. 



a. Infection with Monilia albicans. Chronic paronychia is practically 

 constant. The edges of the nail become yellow and eroded or develop a 

 dark stripe, but the nail substance is frequently firm and translucent. Un- 

 even ridges and grooves are probably due to interference with nutrition. 

 Most of these signs are not seen in nails infected with T. gypseum or T. 

 purpureum. 



b. Psoriasis. Pitting of the nails is frequent. Ridges and grooves sometimes 

 develop. Rarely a lesion of psoriasis develops in the nail bed. In this case 

 the lesion is well demarcated, and there may be redness, which fades on 

 pressure over the nail. The color of psoriatic nails usually remains unal- 

 tered, although a yellow tinge may appear. The nail tends to remain firm 

 and translucent. 



c. Pyogenic involvement of the paronychial tissues. This produces an 

 acute, painful, bright red swelling. There may be a hangnail or some 

 evidence of injury. The disease is of a few days' duration. Dystrophy of the 

 nail, as evidenced by ridges and grooves, may result from interference with 

 nutrition. 



d. Syphilis. This disease may affect the nail or the paronychial tissues. A 

 chancre may appear, and considerable destruction of tissue with painful 

 swelling of the parts is common. Another form of syphilitic involvement 

 of the ungual tissues, usually seen in association with a late cutaneous or 

 other manifestation, results in atrophy ol the nail. 



e. Other diseases. Tuberculosis and leprosy also affect nails and the sur- 

 rounding tissues, dystrophies of varying degrees being present. 



f. Other fungous infections. In the clinical diagnosis of fungous infection 

 of the nails, one should remember that chronic paronychia with secondary 



