Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (364 page)

   Laboratory findings due to involvement of other organs (CNS, liver, kidneys, GI tract, testes)

   Laboratory and clinical findings related to therapy:

   Cytopenias

   Peripheral neuropathies

   As the result of infections

   Gonadal dysfunction

   History of AIDS

Suggested Readings

Jaffe ES, Harris LN, Stein H, et al. Classification of lymphoid neoplasms: the microscope as a tool for disease discovery.
Blood.
2008;112:4384–4399.

Swedlow SH, Campo E, Harris NL, et al.
WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues
, 4th ed. Lyon, France: International Agency for Research on Cancer; 2008:158–166.

BURKITT LYMPHOMA (BL)

   Definition

BL is a highly aggressive, B-cell lymphoma with distinctive morphologic, genetic, and cytogenetic alterations. Translocations involving the MYC oncogene are the molecular hallmark of BL, being present in 100% of cases. There are three distinctive forms of BL: endemic (in Equatorial Africa), sporadic (in Western countries), and associated with immunodeficiency.

   Who Should Be Suspected?

  1.  For the endemic form is the most common childhood cancer in equatorial Africa. It is manifested as tumors of the jaw or facial bones. Nearly all endemic cases are associated with EBV infection.

  2.  The sporadic forms involve mostly nonhematopoietic organs, with a predication to invade the bone marrow and CNS. The peak incidence is in the second and third decades. BL has a propensity to invade. Only 20% of cases are associated with EBV infection.

  3.  Immunodeficiency-associated BL occurs most commonly in patients infected with HIV (HIV-BL), but rarely in other immunocompromised patients.

   Laboratory Findings

   
For diagnosis, a biopsy with studies of morphologic, genetic, and cytogenetic analysis and immunophenotyping is necessary.

   
Morphology
: Medium-sized uniform-appearing cells with round nuclei and 2–5 basophilic nucleoli. The cytoplasm of BL cells is deeply basophilic, with numerous lipid vacuoles. A “starry sky” pattern is characteristic for BL-positive biopsies.