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age range (third to fifth decades) of higher prevalence of AIDS. However, HL is seen less
frequently than high-grade lymphomas in patients with AIDS. HL that occurs in patients with
AIDS more often demonstrates a high stage (III or IV), a propensity for extranodal involvement,
an increased frequency of depleted and sarcomatoid morphologic features, and more often a
mixed cellularity histologic type with fibrohistiocytoid stromal cells. The immunophenotype of
HL in HIV infection is similar to that in persons without HIV infection.[562,564] Small cell
lymphomas of follicular type appear in AIDS similar to those seen in individuals without HIV
infection.

MULTICENTRIC CASTLEMAN DISEASE.-- Multicentric Castleman disease (MCD)
is a lymphoproliferative disorder associated with inflammatory symptoms and interleukin 6 (IL-
6) dysregulation; it is characterized by lymphadenopathy and microscopic findings of
angiofollicular hyperplasia and plasma cell infiltration. The appearance of MCD in persons
infected with HIV is associated with the human herpesvirus 8 (HHV-8) that is also associated
with lesions of Kaposi’s sarcoma (KS). Patients with MCD may subsequently develop other
HHV8-associated lesions including non-Hodgkin lymphoma and primary effusion lymphoma.
Most patients will have a polyclonal gammopathy. The prognosis is poor, with median survival
of 48 months from the time of diagnosis and a 15-fold increased risk for development of non-
Hodgkin lymphoma.[834] With CT imaging, there is hepatosplenomegaly mediastinal or
peripheral lymphadenopathy, and pulmonary bronchovascular nodularity.[835]
Of the two main pathologic types of MCD, hyaline-vascular and plasma cell variants, the
latter is more frequently seen in association with HIV infection. The hyaline vascular type of
MCD shows small hyalinized germinal centers surrounded by concentric layers of small
lymphocytes, interfollicular vascular hyperplasia, hyalinized vessels, and stromal cell
proliferations. The plasma cell type of MCD has hyperplastic, poorly defined lymphoid follicles
with large, active germinal centers surrounded by a narrow mantle of small lymphocytes. The
interfollicular areas are expanded by sheets of plasma cells, but may contain hyalinized vessels.
There are increased numbers of medium-sized to large plasmablasts, resembling immunoblasts,
that contain a moderate amount of amphophilic cytoplasm and a large vesicular nucleus with 1–2
prominent nucleoli. Plasmablasts can comprise up to 50% of the follicular mantle zone in some
follicles, may colonize germinal centers, and may coalesce into microlymphomas.[836]