Tinea imbricata is a superficial fungal infection, a variant of tinea corporis, characterized by concentric lesions.
The pathogen is trichophyton concentricum, often transmitted by close contact. Sometimes, some family members can be infected concurrently, more common in male adults.
Signs and Symptoms
The disease occurs mostly in adult males, rarely in children. The skin lesions are initially small, skin colored or brown spots, gradually expanding into annular lesions, with grayish white, thin scales on the surface. Central scales are ruptured and separated, the outer edges adhere to the epidermis, and the inner edges are freed centripetally. After an annular lesion is formed, a new, small, brown spot occurs in the center of the skin lesion and also develop into an annular lesion, repeatedly. The distance between annual lesions is about 2mm, and up to 10, concentric, annular lesions form multi-annular lesions. Peripheral skin is dark brown, subjective symptoms are pruritus, and lichenification may occur due to long-term scratches, thereafter concentric skin lesions may not be obvious.
Figure 1 tinea imbricata
Skin lesions are mostly on the trunk and buttocks, and can extend to the extremities, mouth, lips, nail grooves, and scalp. However, the palms and soles are less affected, and hair and nail plates are not involved.
The occurrence and development of the disease is not obviously associated with seasons, and the disease develops very slow and relapses are often present.
In periodic acid Schiff (PAS) stain or methenamine silver nitrate stain, some fungal hyphae can be seen in the stratum corneum of epidermis. In chronic cases, dermal mild non-specific inflammatory infiltration, including mild eosinophil infiltration, can be found.
The disease can be diagnosed based on the typical clinical presentations, and fungal examinations can assist in the diagnosis.
Treatment of this disease is often difficult. Generally, a combination treatment composed of systemic antifungals, such as fluconazole, itraconazole, and terbinafine, and topical medications, such as benzoic acid, salicylic acid, Iodine, potassium iodide, and menthol, is appropriate.