Localized Pagetoid Reticulosis

A rare variant of mycosis fungoides (MF), a form of cutaneous T-cell lymphoma, characterized by the presence of localized patches or plaques with epidermal hyperplasia and intraepidermal proliferation of neoplastic T-cells, usually involving one extremity.

Epidemiology

The annual incidence of MF and its variants is estimated at between 1/350,000 and 1/110,000, with localized pagetoid reticulosis accounting for less than 2% of MF cases. Exact data on the male to female ratio are unavailable.

Clinical description

Onset usually occurs in the 4th to 5th decade of life, but younger patients may be affected in rare cases. Patients present with solitary psoriasiform or hyperkeratotic patches or plaques. Extracutaneous involvement is exceptional in the solitary variant, but rarely the disease may progress to "conventional" MF.

Etiology

The etiology remains unknown.

Diagnostic methods

The diagnosis is based on clinical presentation and is confirmed by a skin biopsy. Histological findings reveal a hyperplastic epidermis with marked infiltration by atypical "haloed" lymphocytes that have medium-sized, pleomorphic nuclei. Immunohistology shows either a memory T-helper (CD3+, CD4+, CD8-) or a T-cytotoxic (CD3+, CD4-, CD8+) phenotype. CD30 may be positive.

Differential diagnosis

The differential diagnosis includes other epidermotropic lymphomas, such as CD8+ aggressive epidermotropic cytotoxic T-cell lymphoma (aggressive cutaneous T-cell lymphoma: see this term).

Management and treatment

Radiotherapy and surgical excision are the main treatment options. Topical steroids may also be effective.

Prognosis

Localized pagetoid reticulosis is slowly progressive. Prognosis is favorable: disease-related death has never been reported in these patients.