Lymphomatoid papulosis (ORPHA:98842)
Lymphomatoid papulosis (LyP) is a rare cutaneous condition characterized by chronic, recurrent, and self-regressing papulonodular skin eruptions. It belongs to the spectrum of primary cutaneous CD30+ lymphoproliferative disorders, along with primary cutaneous anaplastic large cell lymphoma (primary C-ALCL; see this term) with which it shares overlapping clinical and histopathologic features.
Epidemiology
Exact prevalence is unknown.
Clinical description
LyP lesions develop at any age, more frequently during adulthood (mean age 45 years), as erythematous papules and nodules of less than 1.5-2 cm, grouped in clusters or disseminated throughout the body. Lesions may become necrotic in the center, show pigmentation and leave scarring. They spontaneously regress within 4 to 8 weeks but new lesions can occur at any time. Patients with LyP are at an increased risk of developing cutaneous or nodal lymphoid malignancies such as classic mycosis fungoides, ALCL, and Hodgkin lymphoma (see these terms).
Etiology
Etiology is unknown. In some reports, a correlation has been found between the use of immunosuppressive medication (e.g. anti-tumor necrosis factor (TNF) agents) for the treatment of chronic inflammatory diseases and the occurrence of LyP.
Diagnostic methods
Diagnosis is based on physical examination and medical history, and is confirmed by histopathologic and immunohistochemical evaluation of skin biopsies. Five histologic sub-types have been defined: type A (wedge-shaped mixed infiltrate with CD30+ tumor cells and inflammatory cells), type B (epidermotropic CD30+ T-cell infiltrate resembling MF), type C (sheets of CD30+ large atypical lymphoid cells), type D (CD30+ and CD8+ lymphocytes with cytotoxic TIA-1 staining resembling Berti's lymphoma), and type E (angiocentric and angiodestructive CD30+ T-cell infiltrate). In case of extracutaneous disease, no imagery techniques are recommended for LyP except pulmonary radiography.
Differential diagnosis
Differential diagnosis includes classical mycosis fungoides, primaryC-ALCL, diffuse large B cell lymphoma, Hodgkin lymphoma (see these terms), metastatic melanoma, and squamous cell carcinoma of the skin.
Management and treatment
Treatment includes use of topical steroids in the initial stages of the disease which, in cases with an increase in the number of lesions, is combined with or followed by phototherapy (psoralen-UVA light therapy [PUVA]) or oral low-dose methotrexate (MTX). Treatment does not guarantee total regression of lesions and relapses are common with the use of lower doses or the discontinuation of treatment. Interferon alfa-2a can be used as an alternative to MTX treatment.
Prognosis
Prognosis is good, with a normal life expectancy, even if the disease is chronic with recurring lesions and an increased risk of developing second lymphoid neoplasms (4-25% of patients). Complications due to long-term treatment may also appear and include a higher incidence of non-melanoma skin cancer (due to PUVA) or hepatic fibrosis (due to MTX).

                            Last update: 
                            April 2014


                            - Expert reviewer(s): 
                            Pr Martine BAGOT