Primary cutaneous diffuse large B-cell lymphoma, leg type. Case report

Cutaneous lymphoma includes two subtypes: cutaneous T-cell lymphoma and B-cell lymphoma without evidence of extracutaneous disease at the time of diagnosis, the latter being the least common, identified in 20 to 25 percent of cases. In the World Health Organization classification, three main types of cutaneous B-cell lymphoma are distinguished, among which is primary diffuse cutaneous large B-cell lymphoma, leg type. It is characterized by being of low prevalence, having skin lesions with similar morphology and phenotype, they can arise in sites other than the legs in 10 percent of cases, with histopathology that demonstrates diffuse non-epidermotropic infiltrates, which extend to the subcutaneous tissue and generally show a monotonous population or confluent sheets of large cells with round nuclei and prominent nucleoli, a mixed population of centroblasts and immunoblasts, with mitotic figures, absence of small B cells and few reactive T cells often confined to perivascular areas. It is a rapidly progressive disease in which the favorable prognosis depends on timely diagnosis and treatment, such as the one presented in this case.