Chronic Granulomatous Lymphadenitis



Chronic Granulomatous Lymphadenitis


C. Cameron Yin, MD, PhD









H&E-stained section demonstrates necrotizing chronic granulomatous lymphadenitis. The granulomas are composed of central necrosis surrounded by epithelioid histiocytes and inflammatory cells.






Chronic granulomatous inflammation is formed by a stepwise series of events as listed in this image.


TERMINOLOGY



Synonyms



  • Chronic granulomatous inflammation of lymph node



ETIOLOGY/PATHOGENESIS


Infectious Agents



  • CGL is usually caused by a wide variety of infectious agents including



    • Mycobacteria, bacteria, viruses, fungi, and parasites



    • Chlamydia, spirochetes


  • Infectious CGL can be classified into 3 subgroups based on its etiology



    • Infections caused by well-recognized organisms



      • Mycobacterium tuberculosis is most common


    • Infections caused by organisms identified by molecular methods but not readily isolated by conventional microbiological methods


    • Infectious etiology strongly suspected but causal organisms not yet identified


  • Advances in molecular diagnostic technology have allowed identification of more organisms



    • Previously, cause of these infections was unknown


Other Causes



  • There are a large number of other causes of CGL



    • Foreign bodies or other irritants/antigens


    • Autoimmune diseases/mechanisms



    • Sarcoidosis


    • Granulomas can occur in patients with lymphoma


    • Granulomas also can occur in lymph nodes draining nonhematopoietic neoplasms


Pathogenesis



  • CGL is result of complex interplay of events



    • Invading agent (e.g., bacteria) results in recruitment of monocytes-macrophages from circulation


    • Monocytes-macrophages engulf bacteria



      • Bacteria multiply within macrophages


    • Macrophages process bacteria and present them to activated T-helper cells


    • Release of cytokines and chemokines by activated macrophages and T-helper cells; causes cell lysis


    • Macrophages mature into epithelioid cells or fuse to form multinucleated giant cells


    • Granulomas form when bacteria and debris are surrounded by macrophages and inflammatory cells


CLINICAL ISSUES


Epidemiology



  • Age



    • CGL can occur in any age group


  • Gender



    • No apparent gender predilection


Site



  • Lymph node group involved depends in part on



    • Initiating agent


    • 1st route of entry into body


  • Cervical lymph nodes are most common


  • Any lymph node or lymph node group can be affected


Presentation



  • Lymphadenopathy, localized or generalized


  • May be accompanied by systemic symptoms



Laboratory Tests



  • Microbiologic culture and identification by biochemical methods


  • Serologic tests are helpful in



    • Identifying infectious agents


    • Determining timing of exposure to organism


  • PCR detects infectious agents with high sensitivity



    • Identify infectious agents in diseases that were previously of unknown etiology



Prognosis



  • Depends on specific etiology and therapy


  • Benign clinical course with good prognosis


IMAGE FINDINGS


General Features



  • Well-defined lymph nodes



    • Increased in number &/or size


  • CT scans are 1st-line imaging tool to evaluate lymphadenopathy


  • Standard x-rays and CT scans show consolidation



    • ± central necrosis


MACROSCOPIC FEATURES


General Features



  • Cut surface can appear nodular (if macrogranulomas)


  • Yellow areas can be seen corresponding to necrotic foci


MICROSCOPIC PATHOLOGY


Histologic Features



  • CGL may be classified as immune or foreign body type


  • Immune type



    • Caused by insoluble particles (e.g., bacteria) that elicit cell-mediated immune response


    • Can be further divided into caseating and noncaseating granulomas


    • Caseating granulomas



      • Composed of central areas of coagulative necrosis


      • Peripheral concentric layers of epithelioid cells, Langhans giant cells, lymphocytes, and fibroblasts


      • Organisms may be identified using special stains


      • M. tuberculosis is most common cause of caseating granulomas


    • Noncaseating granulomas



      • Composed of collection of epithelioid cells, Langhans giant cells, lymphocytes, and histiocytes


    • Eosinophils can occur in granulomas caused by parasites


    • Acute inflammatory cells common in granulomas caused by fungi


  • Foreign body type



    • Caused by inert substances such as talc, suture, and lipid


    • Granulomas composed of epithelioid cells, Langhans giant cells, lymphocytes, and histiocytes surrounding foreign body



      • No caseation occurs usually


    • Can often detect foreign body using polarized light


Cytologic Features



  • Epithelioid histiocytes and inflammatory cells can be identified in fine-needle aspiration smears


  • In some cases, granulomas can be recognized


  • Special stains can be performed on smears


ANCILLARY TESTS


Immunohistochemistry



  • Mycobacterial antigens can be detected and typed with monoclonal antibodies conjugated to peroxidase


PCR



  • Highly sensitive and has identified infectious agents in diseases that were previously of unknown etiology



Special Stains



  • Acid-fast bacilli can be demonstrated by Ziehl-Neelsen, Kinyoun, or Fite-Faraco stain


  • Fungal-like organisms can be highlighted with periodic acid-Schiff (PAS) or Grocott methenamine silver stain


  • Gram-positive and gram-negative organisms can be seen with Gram stain


  • Parasites can be highlighted by Giemsa stain


DIFFERENTIAL DIAGNOSIS


Mycobacterium tuberculosis Lymphadenitis

Jul 8, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Chronic Granulomatous Lymphadenitis
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