Clinicopathological features and T-cell receptor gene rearrangement findings of mycosis fungoides in patients younger than age 20 years.

Mycosis fungoides (MF) is the most common form of cutaneous T-cell lymphoma that usually arises in middle-aged or older people. The incidence of childhood MF is low, but studies in childhood MF suggests that the incidence is rising. The number of studies in childhood MF are few and there are currently no studies about childhood MF in Asians. We investigated the clinicopathological features, T-cell receptor (TCR) gene rearrangement findings, treatment and follow up in childhood MF. The retrospective study was performed on a population consisting of 23 MF patients aged 4-19 years. The duration of the disease ranged from 1 month to 10 years (mean, 2.7 years). In Tumor-Node-Metastasis classifications, all cases were confined to stage IA or IB. Histopathological findings revealed epidermotropism and perivascular infiltrates, epidermotropism in the infundibulum, Pautrier's microabscess, haloed lymphocytes, epidermal lymphocytes larger than dermal lymphocytes, atypical cells with hyperchromatic nuclei and wiry bundles of collagen. TCRgamma gene rearrangement was performed except for four patients, and monoclonality was detected in 16 of 19 cases (84%). Treatment was done with psoralen and ultraviolet (UV)A, UVA1, narrow-band UVB, topical steroid, retinoic acid and calcipotriol. Most patients showed a good response. At a mean follow up of 90.4 months, no patient had either an exacerbation of the disease or extracutaneous involvement. Compared with adult-onset MF, MF in children may show a variety of clinical features. It is considered to have a good prognosis. Moreover, histopathological study and TCR gene rearrangement study can help in the diagnosis of MF in children.