A Case-Control Study on the Take-Off Sign in Lesional Skin Biopsies of Patients with Pityriasis Rosea

Lesional histopathological features in pityriasis rosea (PR) are non-specific (1). Our aim here is to investigate whether a histopathological take-off sign (TOS) is associated with PR. We searched our records, and retrieved the 30 most recent patients with PR diagnosed according to a diagnostic criteria (2). Eight records had histopathological images available. For each, we retrieved the next patient record with differential diagnoses of PR (guttate psoriasis, nummular dermatitis, pityriasis versicolor, tinea corporis, drug eruptions) and with histopathological images available. Six (75%) patients (three with typical PR, one with facial lesions, one with actinic PR, one with PR inversus) and no control subject had TOS (Fig. 1). As we proceed from the uninvolved to the lesional skin (opposite to the direction of the disease progression), the superficial layers of stratum corneum gradually elevate while separating from the more basal layers. The floating part then deviates further away from the specimen, akin to an aircraft taking off. All controls (one with nummular dermatitis with id eruptions, two with psoriasis vulgaris, one with pityriasis versicolor, two with tinea corporis, one with secondary syphilis, and one with PR-like drug rash) did not exhibit TOS (twotailed P: less than 0.01). Lesional histopathological changes in PR are non-specific, with interand intra-oedema, focal caps of spongiosis (6-9), Unna’s sign (eczematoid pattern), Lowenbach’s sign (thinning of the granular layer), Sabouraud’s sign (exudating erythrocytes in the papillary dermis, homogenisation of papillary collagen (7), and intraepidermal dyskeratotic keratinocytes (4-5) having been reported. However, the sensitivities are low. The mechanism of TOS is due to peripheral collarette scaling. The morphology of collarette A Case-Control Study on the Take-Off Sign in Lesional Skin Biopsies of Patients with Pityriasis Rosea