trichoscopy has been widely used in the diagnosis and follow - up of hair and scalp disorders . trichoscopic features of pressure - induced alopecia have been scarcely reported in the literature . in this paper , we describe a case of pressure - induced alopecia in which trichoscopic and histopathological findings overlap with those described for alopecia areata . she reported lesions started at the end of an 11-day hospitalization episode due to diabetic ketoacidosis , during which she was unconscious for 4 days . besides type 1 diabetes , the patient had no other diseases and the patient denied head injury . alopecic patches were localized over the occipital and posterior parietal scalp [ figure 1a ] . two lesions were centered by a thick yellow eschar , whereas the third had only an area of central hyperpigmentation . trichoscopy at the periphery of the alopecic patches revealed black dots , broken and dystrophic hairs . dermoscopy - guided punch biopsies of areas presenting broken hairs were performed and revealed hair follicle miniaturization and pigment casts resembling alopecia areata , however without peribulbar inflammatory infiltrate . pressure - induced alopecia ( a ) one patch presents central hyperpigmentation and two a thick yellow eschar . trichoscopy at the periphery of alopecic areas reveal ( b ) broken and dystrophic hairs , and ( c ) numerous black dots . discrete background erythema is present ( 10 ) hematoxylin and eosin stained biopsy specimens from the scalp showing ( a ) hair follicle miniaturization ( 4 ) and ( b ) pigment casts ( 10 ) pressure - induced alopecia or postoperative alopecia presents with patchy hair loss and may have both features of scarring or nonscarring alopecia . it has been reported after long periods of immobilization during surgeries or prolonged hospitalization in intensive care units ( lasting 330 days ) . the most accepted pathophysiology is tissue ischemia resulting from prolonged pressure on the scalp , and compression of the hair follicles with cessation of their activity . there may be tenderness , swelling , and erythema preceding the hair loss , and in severe cases , skin necrosis , ulceration , and scarring ensues . duration of pressure is more important than its intensity and risk factors include trendelenburg position , obesity , psychiatric disorders , intraoperative hypoperfusion , acidosis , and performance status . even though there normally is a clear history of surgery or prolonged immobilization preceding hair loss , the causality may not be promptly established by the patient or physician . trichoscopy can be misleading , especially in cases without scarring since reported trichoscopic findings resemble alopecia areata , as was observed in our patient . histopathology of pressure - induced alopecia may also share features with alopecia areata , emphasizing the importance of clinical suspicion . the acute injury to anagen hair follicles that occur in pressure - induced alopecia , alopecia areata , and also chemotherapy - induced alopecia might explain the similarity of trichoscopic and histopathological findings in these conditions . most patients will present complete and spontaneous hair regrowth within few months , but scarring may happen , especially in cases that present with ulceration from the beginning . even though trichoscopy and histopathology suggest a noncicatricial process in our patient , assessing the possibility of hair regrowth in the center of the lesions presenting with an eschar will only be possible with patient follow - up . we present a case of pressure - induced alopecia in which dermoscopic and histopathological features overlap with those described for alopecia areata .
pressure - induced alopecia is an unusual cause of hair loss , and reports of its trichoscopic features are scarce . in this paper , we describe a case of pressure - induced alopecia in which trichoscopic and histopathological findings overlap with those described for alopecia areata .