Primary Cutaneous Anaplastic Large Cell Lymphoma

Primary cutaneous anaplastic large cell lymphoma (C-ALCL) is a rare T-cell non-Hodgkin lymphoma that affects the skin and generally shows no extracutaneous involvement at presentation. It belongs to the spectrum of primary cutaneous CD30+ lymphoproliferative disorders along with lymphomatoid papulosis (see this term) with which it shares overlapping clinical and histopathologic features.

Epidemiology

The prevalence of primary C-ALCL is unknown but it accounts for approximately 9% of cutaneous lymphomas. The male/female ratio is of 3:2.

Clinical description

Primary C-ALCL generally occurs in adults and rarely in children and adolescents. Large solitary or multiple slow-growing erythematous skin plaques, nodules or tumors develop, in either a localized or multifocal distribution. These lesions may ulcerate and/or itch. In 10% of cases, primary C-ALCL extends beyond the skin to lymph nodes and manifests as a painless swelling, especially in the neck, armpit or groin. It can also extend to extranodal sites. General symptoms, usually present in cases with extracutaneous involvement, include loss of appetite, weight loss, fatigue, and night sweats (B symptoms).

Etiology

Etiology is unknown.

Diagnostic methods

Diagnosis is based on physical examination and medical history, and is confirmed by histopathological and immunohistochemical evaluation of skin biopsies showing cell infiltrates of anaplastic cytology (atypical large cells with abundant cytoplasm, prominent nucleoli, and horseshoe-like or reniform nuclei), within the dermis or subcutis, with constant membrane expression of the CD30 T-cell antigen in the majority (>75%) of neoplastic cells, a variable loss of pan-T antigens (CD2, CD3, CD5), and a lack of expression of epithelial membrane antigen (EMA) and CD15. Additional tests include blood analysis and imagery (PET-scan, CT-scan, MRI) that are used to differentiate the cutaneous from the systemic form.

Differential diagnosis

Differential diagnosis includes lymphomatoid papulosis, metastatic melanoma, squamous cell carcinoma, diffuse large B cell lymphoma and Hodgkin lymphoma (see these terms).

Management and treatment

If lesions are solitary or localized to a single area, excision and/or radiation therapy is performed. If lesions are disseminated in multiple sites on the body, chemotherapy with CHOP (cyclophosphamide, doxorubicin, vincristine and prednisone) or CHOP-like regimens constitutes the first-line treatment. Chemotherapy can be combined with autologous stem cell transplantation. Recently, anti-CD30 monoclonal antibody therapy (e.g. brentuximab vedotin) has emerged as a promising alternative therapeutic option.

Prognosis

The prognosis is generally good, with a five-year survival rate of 90%. In 25% of cases, spontaneous regression is observed. Relapses, generally without any extracutaneous dissemination, may sometimes occur (approximately in 30% of cases).