Precursor B lymphoblastic lymphoma presenting as lytic bone lesions.

Area of Science:

• Hematology
• Oncology
• Pathology

Background:

• Precursor B lymphoblastic lymphoma (B-LL) is an aggressive hematologic malignancy.
• B-LL commonly affects skin and lymph nodes, but can present as lytic bone lesions.
• Differential diagnosis in bone includes small round blue cell tumors, diffuse large B-cell lymphoma, and acute myelogenous leukemia.

Purpose of the Study:

• To describe the morphologic and immunophenotypic characteristics of B-LL presenting with bone lesions.
• To highlight the importance of immunophenotyping for accurate diagnosis.

Main Methods:

• Retrospective analysis of 4 patients (2 children, 1 teen, 1 adult) with bone pain and osteolytic lesions.
• Morphologic assessment and immunohistochemical staining of neoplastic cells.
• Panel of antibodies included CD10, CD20, CD34, CD43, CD45/CD45RB, CD79a, CD99 (MIC2), and terminal deoxynucleotidyl transferase (TdT).

Main Results:

• All 4 patients presented with bone pain and osteolytic lesions, without peripheral blood or iliac bone marrow involvement.
• Immunohistochemical staining revealed positivity for CD43 (4/4) and TdT (4/4).
• Additional markers showed heterogeneity: CD10 (3/4), CD20 (3/4), CD34 (1/4), CD45/CD45RB (2/4), CD79a (4/4), CD99 (MIC2) (2/4). CD3 was negative in all cases.

Conclusions:

• Precursor B lymphoblastic lymphoma can manifest primarily in bone with osteolytic lesions.
• Immunophenotypic heterogeneity necessitates a comprehensive antibody panel for accurate diagnosis.
• Timely diagnosis through immunophenotyping is essential for effective treatment of this curable malignancy.