Clonal Rearrangement of the T Cell Receptor $ Gene in the Circulating Lymphocytes of Erythrodermic Follicular

F OLLICULAR MUCINOSIS is a histologic process whose hallmark is the accumulation of acid mucopolysaccharides within hair follicle epithelium.’ Follicular mucinosis has been reported in four clinical settings.”7 In the first group of cases, follicular mucinosis occurs as slightly raised and boggy plaques on the face and scalp, usually of children, adolescents, or young adults. A second group has, in addition to lesions on the head, involvement of the trunk and extremities, usually as plaques, but occasionally as widespread follicular papules; a variety of systemic processes have been seen in association with this type of presentation. In either setting, areas of hair loss due to follicular mucinosis are referred to as alopecia mucinosa, and such hair loss is often the presenting complaint. In a third group of cases, follicular mucinosis occurs within the plaques of cutaneous T cell lymphoma, most typically of the mycosis fungoides type and rarely, Sezary’s syndrome.8 A fourth group comprises a wide variety of cutaneous neoplasms and inflammatory conditions within which follicular mucinosis has been reported as an incidental microscopic finding, affecting only a few hair follicles.’ An unusual and distinct presentation has recently been reported as enythrodermic follicular mucinosis.9 The patient who was the subject of that report had widespread follicular papules over most of the skin, as well as alopecia. On hematologic examination there was relative and absolute eosinophilia, and increased numbers of “activated” circulating T cells. We recently encountered a 1 2-year-old girl who presented with erythrodermic follicular mucinosis whose peripheral blood eosinophilia was accompanied by massive eosinophilic infiltrates in the lungs. The patient’s blood was found to contain a preponderance of morphologically and immunophenotypically abnormal T lymphocytes with a clonal pattern of rearrangement of the T cell receptor (TCR) /3 gene. Our data strongly suggest that a T cell neoplasm is the underlying process in this unusual condition.