A 30-year-old Caucasian man presented with a left-lower-extremity posterior thigh area skin lesion. The lesion had started as a rash 3 months prior, and in time turned into an ulcerated open wound with some nodularity in and around it. Initial treatments with topical measures, oral antibiotics, and wound care consolidation did not help. There was no history of fevers, chills, night sweats, or weight loss. Physical examination revealed no organomegaly or lymphadenopathy. A biopsy of the skin lesion revealed extensive involvement of skin and subcutaneous tissue by sheets of large atypical cells (A), including C-shaped and multinucleated cells (B) with strong positivity for CD30, CD2, CD45, granzyme B (C), and EMA (epithelial membrane antigen). Immunoperoxidase stains were negative for CD20, PAX5, ALK, pankeratin, S100, MART-1, CD34, and P63.
D. Anaplastic large T-cell lymphoma
Angioimmunoblastic lymphoma is a type of peripheral T-cell lymphoma that is clinically characterized by a high fever and generalized lymphadenopathy. In advanced cases, hepatosplenomegaly, hemolytic anemia, and polyclonal hypergammaglobulinemia may occur. Approximately 40% to 50% of patients may have cutaneous involvement. Clinical and immunophenotypic features of our case makes this diagnosis unlikely.
Primary cutaneous B-cell lymphomas represent 20% to 25% of all cutaneous lymphomas, and can manifest as patches, plaques, and nonulcerated nodules. The involvement is characterized by nodular or diffuse, often sharply demarcated, nonepidermotropic lymphoid infiltrates; these are predominantly located in the dermis, sparing the subepidermal zone. B-cells stain positively for CD19, CD20, CD79, mu (IgM) or gamma (IgG) immunoglobulin (Ig) heavy chains, and kappa or lambda Ig light chains. They are negative for T-cell markers (ie, CD2, CD3, CD4, CD7, and CD8). Clinical and immunophenotypic features of our case make this diagnosis unlikely.
Peripheral T-cell lymphomas are a heterogeneous category of nodal and extranodal mature T-cell lymphomas. In most cases, there is peripheral lymph node involvement; however, any site may be affected, and there is often infiltration of bone marrow, liver, spleen, and extranodal tissues. Extranodal presentation occurs most commonly in the skin and gastrointestinal tract. These cases are ALK- and CD30-negative. Clinical and immunophenotypic features of our case make this diagnosis unlikely.
AAnaplastic large cell lymphomas are distinguished from other lymphomas by their anaplastic cytology and constant membrane expression of the CD30 antigen. Striking clinical features include frequent cutaneous and extranodal involvement, young age at presentation, and male predominance. Morphologic and immunostaining findings of this case support the diagnosis of ALK-negative anaplastic large cell lymphoma of T-cell origin. The expression of EMA argues against primary cutaneous anaplastic large cell lymphoma.