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expansion of EBV-infected B-lymphocytes. Mutations in bcl-6 regulatory regions may also be
present.[561,567]
The high grade nature of most AIDS associated lymphomas helps in diagnosis, which can
be difficult because of routinely employed biopsy procedures that may yield a small amount of
tissue. Whether the tissue is obtained by stereotaxic brain biopsy, bronchoscopic lung biopsy, or
endoscopic gastrointestinal biopsy, small tissue samples are usually obtained.
Immunohistochemical staining may aid in defining a monoclonal cell population consistent with
a neoplastic proliferation. Staining with common leukocyte antigen (CLA) may be useful in
identifying the nature of lymphomatous infiltrates when necrosis is extensive.
Malignant non-Hodgkin lymphomas lead to the death of adult AIDS patients in over half
of cases when this neoplasm is present at autopsy. Organ involvement leading to death is
divided almost evenly among the central nervous system, gastrointestinal tract, and respiratory
system. Chemotherapy protocols usually do not significantly alter the course of malignant
lymphomas in patients with AIDS. There may be a short initial response, but virtually all
lymphomas relapse, with an average time from diagnosis to death of less than a year.[417,569]

PRIMARY BODY CAVITY-BASED LYMPHOMAS.-- A small number of AIDS-
associated NHL’s may appear only as malignant cells within body cavity effusions without
evidence for a mass lesion, organomegaly, or lymphadenopathy. These primary body cavity-
based lymphomas (BCBLs), also known as primary effusion lymphoma (PEL), have occurred in
pleural effusions, pericardial effusions, or ascites. The prognosis is poor. They are associated
with the same herpesvirus-like agent, known as Kaposi sarcoma herpesvirus / human herpesvirus
8 (KSHV/HHV8), as lesions of Kaposi sarcoma. There is frequent presence of the Epstein-Barr
virus and no associated c-myc gene rearrangement, similar to the high-grade non-Hodgkin
lymphomas seen elsewhere. The primary body cavity based lymphomas are of a large cell
variety, often with some features of plasma cell differentiation. Cytologic features include large
cell size, moderate to abundant cytoplasm, a single nucleus in most cells with occasional bi- or
multinucleated giant cells, single to multiple prominent nucleoli, and coarse chromatin.
Reported immunophenotypes include the following markers: CD30, CD38, CD45, CD71, and
EMA. Their prognosis is poor.[570,571] Some high grade B cell non-Hodgkin lymphomas that
are HHV-8 positive occur as solid masses, and their morphologic and immunophenotypic
characteristics and prognosis are similar to PEL. They may be termed extracavitary PELs.[572]

MALT LESIONS.-- Mucosa-associated lymphoid tissue (MALT) lesions are lymphoid
proliferations that typically occur at extranodal sites such as the gastrointestinal tract, bronchi,
and salivary glands. Such MALT lesions have been described in association with both adult and
pediatric AIDS. The spectrum of lesions has included myoepithelial sialadenitis (MESA) with
low-grade MALT lymphoma, low-grade MALT lymphoma, diffuse large cell lymphoma, and
atypical pulmonary lymphoid hyperplasia and lymphoid interstitial pneumonitis complex. These
lesions appear to follow an indolent course in children. Unlike the MALT lesions seen in other
immunocompromised adults that regress when immune suppression is reduced, as in transplant
recipients, those in adults with AIDS have an aggressive course with poor prognosis.[573,574]

ANAPLASTIC LARGE CELL LYMPHOMAS.-- Several peripheral T-cell lymphoma
(PTCL) subtypes have been described in association with HIV infection, most often PTCL-not
otherwise specified, and anaplastic large cell lymphoma (ALCL). Such HIV-associated ALCLs