Abstract

Pressure alopecia (PA) is an uncommon but clinically distinctive form of hair loss occurring after prolonged pressure due to ischemia. It is typically reported to occur in the post-operative period, intensive care unit patients or other clinical scenarios with prolonged bed rest or incapacitation.The limited histopathological description of PA frequently includes overlapping features with alopecia areata (AA) and trichotillomania : an apparent nonscarring process, prominent non-anagen follicles, perifollicular inflammatory infiltrate, luminal pigment casts ; along with other features including intravascular thrombosis, apoptosis and fat necrosis in a few reported cases. We report a case of a middle-aged female with past medical history of long QT syndrome, presenting with rapid-onset itching and significant hair loss, approximately two weeks after hospitalization, ICU stay and intubation; in the setting of multiorgan system failure. Physical examination revealed a tender patch of sharply circumscribed alopecia without clinical signs of scarring on her posterior scalp.  A punch biopsy demonstrated multiple features resembling AA, including a significant non-anagen shift, dilated follicular ostia and pigment casts. Clinico-pathological correlation, with consideration of the rapid timecourse after hospitalization and strong localization of hair loss to areas of prolonged pressure during intubation, supported a diagnosis of PA.  Interestingly, the deep dermis and superficial subcutis demonstrated a mild lymphocytic infiltrate with eosinophils perivascularly and within fibrous tracts. Eosinophils have been previously reported in up to half of AA cases in some studies, but are not well-described in PA.  This finding highlights the continuing significant overlap between these two entities microscopically and may lend further support to hypotheses of a related pathogenesis.