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Case 143 - Discussion

Hematopathology Case

 

Diagnosis: HIV lymphadenitis, chronic phase.

The patient had another lymph node excision 3 years ago (case HP-142)

 

Human Immunodeficiency Virus (HIV) Lymphadenitis

  • Clinical

    • HIV gp120 binds to CD4 on human cells

    • In Africa and India, the most common lymphadenitis in HIV+ persons is tuberculosis infection, whereas in the United States and Latin America, Histoplasmosis and Pneumocystosis infections are the usual complications.

    • Patients typically show generalized or progressive lymphadenopathy.

  • Histopathology of Acute Phase (Phase A)

    • Florid follicular hyperplasia: large geographic germinal centers, prominent starry-sky appearance with apoptosis and phagocytosis of nuclear debris by tingible-body histiocytes, numerous centroblasts in mitosis

    • Naked germinal centers with diminished or absent mantle zone

    • Follicular lysis or invagination of small mantle zone lymphocytes into the germinal centers

    • Nonspecific focal interfollicular hemorrhages, unrelated to the biopsy procedure

    • Interfollicular prominent plasmacytosis, scattered immunoblasts, and increased vascularity

    • Warthin-Finkedey giant cells: grapelike cluster of overlapping nuclei, randomly throughout the nodal parenchyma, CD2+ and CD35+, represent a multinucleated form of follicular dendritic cells

    • Aggregates of monocytoid cells located next to blood vessels and sinuses

  • Histopathology of Chronic Phase (Follicular Involution, or Phase B)

    • Mixed follicular hyperplasia and involution with reactive and regressive germinal centers

    • Disruption of dendritic cell networks, depletion of lymphocytes, accumulation of plasma cells, and excessive proliferation of blood vessels in and around the lymphoid follicles

    • The small atrophic germinal centers may be hyalinized or show deposition of proteinaceous material

  • Histopathology of Burnout Phase (Lymphoid depletion, or Phase C)

    • Atrophic, burned-out follicles and extensive, diffuse vascular proliferation

    • Follicles are small and depleted of lymphocytes, often with a central transfixing, collagen-ensheathed arteriole and deposits of PAS+ material (“lollipop” follicle)

    • The follicles are often inconspicuous and focally or entirely hyalinized

    • The interfollicular cortex shows a significant loss of lymphocytes and excessive vascularization, with frequent plasma cells and diffuse fibrosis

  • DDX:

    • Acute phase: infectious mononucleosis, cytomegalovirus, measles, and varicella lymphadenitides show similar germinal center changes and may be impossible to distinguish based on morphology grounds alone. Serologic testing for specific antibodies is necessary in all viral infections.

    • Chronic phase:

      • Castleman disease: similar involuted follicles with hyaline germinal centers and vascular proliferation, but lack of lymphocyte depletion, HIV-

      • Angioimmunoblastic lymphadenopathy

References:

    1. AFIP, Benign and reactive conditions of lymph node and spleen, series 4

    2. Ioachim's Lymph Node Pathology, 4th edition