The histology of palpable masses exhibit a different pathological picture: the tumor masses have multinodular areas that consist of necrosis or fibrous tissue interspaced with areas that consist of large neoplastic cells that have abundant cytoplasm and abnormally shaped nuclei within a fibrotic and chronic inflammatory cell background. Again, typical ALCL-defining "hallmark" cells may be difficult to find in these masses. The effusions show abundant, uniform-appearing, non-cohesive large cells with irregularly-shaped nuclei, prominent nucleoli and abundant cytoplasm. The histology and pathological features of diseased lymph nodes and tissues outside of the breast implant are indistinguishable from those seen in ALK-negative ALCL. The neoplastic cells in the capsules, effusions, and tissues strongly and uniformly express CD30, CD4 (75–84% of cases), EMA (48–90%), CD43 (86-95%), CD45 (44-74%), and in a far fewer percentage of cases various other marker proteins. These cells do not express ALK and often lack the characteristic surface marker proteins of T-cells. Identification of the status of these markers helps diagnose the disease. Gene and molecular abnormalities
No chromosome translocations, chimeric genes, or fusion proteins have been described in BIA-ALCL although the neoplastic cells in the disease have been described to have gene copy number variations involving gains in gene copies on the p arm of chromosome 19 and losses of gene copies in the p arms of chromosome 10 and 1. The neoplastic cells in BIA-ALCL show mutations of the STAT3 gene in 64% of cases and reports of mutations in JAK1, JAK3, DNMT3A, and TP53 genes.
These as well as individuals who relapse after front-line therapy need further treatment. In one study of 65 patients with pcALCL, 95% treated with surgical excision achieved complete remission but 41% of them relapsed within 22 months while 64% of patients treated with surgery plus radiotherapy developed recurrent disease within 55 months. In another study of 135 patients with this disease, 39% had relapses limited to the skin, 15% developed extracutaneous disease, and 9% ultimately died from pcALCL. Individuals with refractory, recurrent, and/or extensive disease have been treated more aggressively. In various studies, 10 of 13 such patients responded within 4 weeks to treatment with the chemotherapeutic agent, methotrexate; 10 of 16 patients obtained complete remissions of their skin lesions when treated with the anti-CD30 monoclonal antibody, brentuximab verdotin, and 48 of 53 patients treated with the aggressive chemotherapeutic CHOP regimen had complete responses. However, most of these patients developed recurrent disease within four months. As currently recommended, brentuximab vedotin is use initially to treat widespread systemic disease; a single chemotherapeutic drug rather than aggressive combination chemotherapy with CHOP or similar regimens is used to treat patients not responding to brentuximab verdotin; aggressive chemotherapy regimens are used to treat widespread nodal and/of visceral disease and disease which failed on other regiments; and, although there is little data supporting this, employ allogeneic bone marrow transplantation for patients with multiple relapses that have progressed on systemic therapy. Recurrences, regardless of treatment type, are common. pcALCL has an estimated five-year failure-free survival rate of 55 percent.