Chronic Granulomatous Lymphadenitis



Chronic Granulomatous Lymphadenitis


C. Cameron Yin, MD, PhD










Paraffin section shows 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


Abbreviations



  • Chronic granulomatous lymphadenitis (CGL)


Synonyms



  • Chronic granulomatous inflammation of lymph node


Definitions



  • Granulomatous inflammation is a specific type of inflammatory response



    • Characterized by accumulation of modified macrophages (epithelioid cells)


    • Initiated by infectious or noninfectious agents


    • Requires poorly digestible irritants and T-cell mediated immunity directed at irritant


  • Chronic granulomatous lymphadenitis is characterized by



    • Accumulation of activated macrophages and inflammatory cells forming granulomas within lymph node



      • Results from deposition of indigestible antigenic material within tissue


    • Often associated with necrosis or acute inflammation


ETIOLOGY/PATHOGENESIS


Infectious Agents



  • CGL is usually caused by 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 is strongly suspected, but causal organisms have not yet been 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



      • e.g., 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



    • Presence of invading agent (e.g., bacteria) in tissue 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 general


  • 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


  • Polymerase chain reaction (PCR) methods detect infectious agents with high sensitivity



    • Infectious agents have been identified in diseases that were previously of unknown etiology


Treatment



  • Empiric antibiotics


  • Antituberculous therapy


  • Surgical manipulation


Prognosis



  • Depends on specific etiology and therapy administered


  • 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



    • With or without 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 further divide these 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 by 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, lipid


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



      • No caseation occurs usually



    • Can often detect foreign body by 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 previously had no known 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

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