Trichoscopy of Noncicatricial Pressure-induced Alopecia Resembling 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.

INTRODUCTION

Trichoscopy has been widely used in the diagnosis and follow-up of hair and scalp disorders.[1] Pressure-induced alopecia is an unusual cause of hair loss.[2] Trichoscopic features of pressure-induced alopecia have been scarcely reported in the literature.[3] In this paper, we describe a case of pressure-induced alopecia in which trichoscopic and histopathological findings overlap with those described for alopecia areata.

CASE REPORT

A 14-year-old girl presented with a 2-month history of patchy hair loss. 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. Discrete underlying erythema was noted in some areas [Figure 1b and c]. Pull test was negative. 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. There were no signs of scarring [Figure 2a and b].

Figure 1

Pressure-induced alopecia (a) one patch presents central hyperpigmentation and two a thick yellow eschar. Numerous black dots can be seen with the naked eye. Trichoscopy at the periphery of alopecic areas reveal (b) broken and dystrophic hairs, and (c) numerous black dots. Discrete background erythema is present (×10)

Figure 2

Hematoxylin and eosin stained biopsy specimens from the scalp showing (a) hair follicle miniaturization (×4) and (b) pigment casts (×10)

DISCUSSION

Pressure-induced alopecia or postoperative alopecia presents with patchy hair loss and may have both features of scarring or nonscarring alopecia.[4] It has been reported after long periods of immobilization during surgeries or prolonged hospitalization in Intensive Care Units (lasting 3–30 days).[5]

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.[3] There may be tenderness, swelling, and erythema preceding the hair loss, and in severe cases, skin necrosis, ulceration, and scarring ensues.[4] Duration of pressure is more important than its intensity and risk factors include Trendelenburg position, obesity, psychiatric disorders, intraoperative hypoperfusion, acidosis, and performance status.[267]

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,[5] 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.[13]

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.[7] 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.

CONCLUSION

We present a case of pressure-induced alopecia in which dermoscopic and histopathological features overlap with those described for alopecia areata. Permanent hair loss is a clue to differential diagnosis since alopecia areata is noncicatricial. However, scarring is not always present. Once the temporal relation with head immobilization is established, the diagnosis becomes obvious.

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Conflicts of interest

There are no conflicts of interest.