Page 360 - Textbook of Pathology, 6th Edition

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SECTION II
Figure 14.2 Reactive lymphadenitis, follicular hyperplasia type. Figure 14.3 Reactive lymphadenitis, sinus histiocytosis type.

hyperplasia. The condition may occur at any age and 3. Sinus histiocytosis or sinus hyperplasia is a very
possibly has an association with Epstein-Barr virus common type found in regional lymph nodes draining
infection. Two histologic forms are distinguished: inflammatory lesions, or as an immune reaction of the host
i) Hyaline-vascular type is more common (90% cases) and to a draining malignant tumour or its products. The
is characterised by the presence of hyalinised arterioles hallmark of histologic diagnosis is the expansion of the
in small lymphoid follicles and proliferation of vessels in sinuses by proliferating large histiocytes containing
the interfollicular area. phagocytosed material (Fig. 14.3). The presence of sinus
ii) Plasma cell form is less common and is characterised histiocytosis in the draining lymph nodes of carcinoma
by plasma cell hyperplasia and vascular proliferation in such as in breast carcinoma has been considered by some
the interfollicular region. workers to confer better prognosis in such patients due to
good host immune response.
2. Paracortical lymphoid hyperplasia is due to hyper-
plasia of T-cell-dependent area of the lymph node. Sinus histiocytosis with massive lymphadenopathy is
Amongst the important causes are immunologic reactions characterised by marked enlargement of lymph nodes,
caused by drugs (e.g. dilantin), vaccination, viruses (e.g. especially of the neck, in young adolescents. It is associated
infectious mononucleosis) and autoimmune disorders. Its with characteristic clinical features of painless but massive
histologic features are: lymphadenopathy with fever and leucocytosis and
i) Expansion of the paracortex (T-cell area) with increa- usually runs a benign and self-limiting course.
sed number of T-cell transformed immunoblasts. HIV-related Lymphadenopathy
ii) Encroachment by the enlarged paracortex on the
lymphoid follicles, sometimes resulting in their efface- HIV infection and AIDS have already been discussed in
Haematology and Lymphoreticular Tissues
ment. Chapter 4; here one of the frequent finding in early cases of
iii) Hyperplasia of the mononuclear phagocytic cells in AIDS, persistent generalised lymphadenopathy (PGL), is
the lymphatic sinuses. described. The presence of enlarged lymph nodes of more
Variants of paracortical lymphoid hyperplasia are than 1 cm diameter at two or more extra-inguinal sites for
angio-immunoblastic lymphadenopathy, dermatopathic more than 3 months without any other obvious cause is
lymphadenopathy, dilantin lymphadenopathy and post- frequently the earliest symptom of primary HIV infection.
vaccinial lymphadenopathy. Histologically, the findings at biopsy of involved lymph
Angioimmunoblastic lymphadenopathy is characterised node vary depending upon the stage of HIV infection:
by diffuse hyperplasia of immunoblasts rather than 1. In the early stage marked follicular hyperplasia is the
paracortical hyperplasia only, and there is proliferation dominant finding and reflects the polyclonal
of blood vessels. The condition occurs in elderly patients B-cell proliferation.
with generalised lymph node enlargement and 2 In the intermediate stage, there is a combination of
hypergammaglobulinaemia. follicular hyperplasia and follicular involution. However,
Dermatopathic lymphadenopathy occurs in lymph node adenopathic form of Kaposi’s sarcoma too may develop
draining an area of skin lesion. Besides the hyperplastic at this stage (page 414).
paracortex, there is presence of dark melanin pigment 3. In the last stage, there is decrease in the lymph node
within the macrophages in the lymph node. size indicative of prognostic marker of disease