De novo double-hit B-cell precursor leukemia/lymphoma - an unusual presentation as peritoneal lymphomatosis

Peritoneal lymphomatosis (PL) is a rare presentation of extranodal precursor leukemia/lymphoma. The presentation is often non-specific, leading to delayed diagnosis and treatment. In this case, though the preliminary diagnosis was established on ascitic fluid cytology, the disease progressed rapidly, leading to demise before initiating chemotherapy. Immunophenotyping and molecular studies, performed later, established a diagnosis of de novo B-cell precursor leukemia/lymphoma with MYC, BCL2 rearrangements (Double-hit lymphoma). MYC, BCL2 rearrangements are rarely reported in precursor B-lymphoma/leukemia which carry dismal prognosis. In this report, we illustrate autopsy findings of PL in an elderly gentleman who presented with ascites for evaluation.

CALLA negative precursor B lymphoblastic leukemia with MLL gene translocation and an unusual FISH signal pattern.

Rearrangements of the mixed lineage leukemia (MLL) gene at 11q23 commonly occur in infants with CALLA negative B lymphoblastic leukemia (B-ALL). Most often, these are detected by conventional karyotyping; however, fluorescent in-situ hybridization (FISH) with the help of a dual-color break-apart probe is used to identify cryptic translocations. When there is an MLL gene translocations the usual FISH signal pattern is 1 red-1 yellow fusion signal pattern We present a case of an infant with CALLA negative precursor B-ALL with a characteristic translocations t(4;11) (q21;q23),however,with an unusual MLL FISH signal pattern.

Dificuldade diagnóstica em dois casos de neoplasia de células linfóides precursoras cutâneas primárias / Diagnostic pitfalls in two cases of primary cutaneous neoplasia of precursor lymphocytes

O linfoma linfoblástico (LLB) é uma neoplasia maligna de linfócitos precursores (B, T ou células NK). O comprometimento primário da pele é raro. Relatamos as características clínicas, anatomopatológicas e imunofenotípicas em dois pacientes com apresentação cutânea primária que, histologicamente, apresentavam infiltrado de células imaturas. A análise imunofenotípica foi realizada com amplo painel de anticorpos. A pesquisa de rearranjo no gene do receptor de células T (TCR-gama) pelo método de reação em cadeia da polimerase (PCR) resultou positiva em um caso, que era CD56 positivo, classificado como linfoma de células NK blásticas-símile. Este caso representa uma entidade distinta derivada de células precursoras num estágio precoce de uma via comum de diferenciação para células T e NK. O outro caso foi classificado como LLB-T com expressão aberrante de CD79a, o que poderia ser erroneamente interpretado. O diagnóstico correto depende da utilização de um amplo painel de anticorpos para caracterização imunofenotípica e avaliação molecular.

The lymphoblastic lymphoma (LBL) is a malignant neoplasm of precursor lymphocytes (B, T or NK-cells). The primary involvement of the skin is rare. We examined the clinical, anatomopathological and immunophenotypic features of two patients with primary cutaneous involvement. Histologically they showed an infiltrate of immature cells. The immunophenotypic analysis was performed with a comprehensive panel of antibodies. T-cell receptor rearrangement (TCR-gamma) was analyzed with polymerase chain reaction (PCR) and it was positive in one case, which was CD56 positive, classified as blastic NK-cell-like lymphoma. This case represents a distinct entity derived from precursor cells at an early stage of a common developmental pathway for T and NK cells. The other case was classified as T-cell lymphoblastic lymphoma with aberrant expression of CD79a, what could be a diagnostic pitfall. The accurate diagnosis depends on the use of a comprehensive panel of antibodies for immunophenotypic characterization and molecular analysis.