Abstract
In dogs, Burkitt-like lymphoma (B-LL) is rare tumor and it is classified as a high-grade B-cell malignancy. The diagnosis is challenging because of the similar histologic appearance with other histotypes, no defined phenotypical criteria and poorly described clinical aspects. The aim of the study was to provide a detailed description of clinical and morphological features, as well as immunophenotypical profile of B-LL in comparison with the human counterpart. Thirteen dogs with histologically proven B-LL, for which a complete staging and follow-up were available, were retrospectively selected. Immunohistochemical expression of CD20, PAX5, CD3, CD10, BCL2, BCL6, MYC, and caspase-3 was evaluated. Histologically, all B-LLs showed a diffuse architecture with medium to large-sized cells, high mitotic rate and diffuse starry sky appearance. B-phenotype of neoplastic cells was confirmed both by flow-cytometry and immunohistochemistry. Conversely, B-LLs were negative for BCL2 and MYC, whereas some cases co-expressed BCL6 and CD10, suggesting a germinal center B-cell origin. Disease stage was advanced in the majority of cases. All dogs received CHOP-based chemotherapy with or without immunotherapy. Despite treatment, prognosis was poor, with a median time to progression and survival of 130 and 228 days, respectively. Nevertheless, ~30% of dogs survived more than 1 year. An increased apoptotic index, a high turnover index and caspase-3 index correlated with shorter survival. In conclusion, canine B-LL shows phenotypical differences with the human counterpart along with features that might help to differentiate this entity from diffuse large B-cell lymphoma.
Highlights
In humans, Burkitt’s lymphoma (BL) is classified as a highly aggressive B-cell lymphoma and was first described by Denis Burkitt in 1958
In human oncology it is still controversial whether a relationship exists between apoptosis and prognosis, but, as a general rule, an increased apoptotic index (AI) is associated with a worse clinical outcome [30] and this may hold true in canine Burkitt-like lymphoma (B-LL) as well
Caution is warranted before concluding that canine B-LL represent true MYC-negative BL
Summary
Burkitt’s lymphoma (BL) is classified as a highly aggressive B-cell lymphoma and was first described by Denis Burkitt in 1958. BL derives from mature germinal or post germinal center B-cells and is further divided into three clinical entities (sporadic, endemic, and immunodeficiencyassociated), all having in common rearrangements of the MYC oncogene. Sporadic BL occurs in children and young adults, accounting for 30–50% of all lymphomas in children. It is more common in males than females. Immunodeficiency-associated BL is more common in patients infected with human immunodeficiency virus (HIV), its occurrence is not related to a low percentage of CD4 positive cells. The variants differ in their association with the Epstein Barr virus, which is present almost always in endemic BL tumor cells and in 20–40% of the other cases
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