168 An Introduction to Medical Mycology 



as belonging to the genus Endodermophyton. Tie lias found four species 

 of Endodermophyta— concentricum, indicum, tropicale and mansoni— to be 



the pathogens responsible. Most workers believe that these are variants of 

 a single species and classify it as Trichophyton. 



Yonng adults are especially likely to contract the disease, and men are 

 more susceptible than women. Children are less prone to develop tinea 

 imbricata. The condition is observed in places where the coconut tree grows. 

 It is fairly common in many of the Pacific islands, in the Malay States and 

 in central and southern China; cases have also been reported from North 

 China. In recent years it has spread to Ceylon and Southern India. Cases 

 have been reported from South Africa and from South and Central Amer- 

 ica, but some doubt has been expressed as to their being tine instances of 

 tinea imbricata (Castellani). 



(b) Clinical characteristics.— The condition begins as one or more 

 brownish spots, which slowly increase in size. The central portion of the 

 superficial epidermis finally becomes detached, the epidermis cracks, and 

 there is an opening from the center toward the border. Around the lesion 

 a brownish zone appears. In this latter site, rupture of the skin again occurs. 

 This process is repeated until numerous rings are formed, more or less con- 

 centrically arranged and imbricated. Other patches develop, and after 

 several months a large portion of the cutaneous surface may be affected. 

 There is little if any visible redness. Scaling may be profuse. Itching is 

 usually intense. The face is often affected. The scalp also may be involved, 

 but the hair follicles are usually spared. The nails may be infected. 



(c) Differential diagnosis.— The absence of redness and the typical 

 concentric rings are evidence against the diagnosis of tinea glabrosa. In a 

 case reported by Kittredge an eruption similar to tinea imbricata was caused 

 by T. purpureum. Ichthyosis is usually present from birth, and the scaling 

 lacks the concentric rings seen in tinea imbricata. 



(d) Prognosis.— Cure is said to be difficult, and relapse is common. 



(e) Treatment.— Castellani advised treatment either with 25 per cent 

 resorcinol in tincture of benzoin or with 5 to 10 per cent ehrysarobin in 

 an ointment base. 



BIBLIOGRAPHY 



Castellani, A.: Tinea imbricata (Tokelau), Brit. |. Dermat. 25:377, 1913; Fungi and fun- 

 gous diseases. Arch. Dermat. c\- Syph. 17:359, 1928. 



10. OTOMYCOSIS (MYRINGOMYCOSIS) 



This rash of the external ear and the aural canal has a mixed and dis- 

 puted etiology; it is marked by an exudative inflammation and pruritus. 



