Pulmonary BALT Hyperplasia



Pulmonary BALT Hyperplasia







Key Facts


Terminology



  • Polyclonal proliferation of small lymphocytes arising within lung parenchyma


Etiology/Pathogenesis



  • Commonly associated with underlying autoimmune disorders such as Sjögren syndrome, rheumatoid arthritis, and collagen vascular diseases


  • Associated with viral infection, including HIV and Epstein-Barr virus


  • Associated with immunodeficiency, including common variable immunodeficiency, AIDS, and bone marrow transplants


Clinical Issues



  • Mostly asymptomatic; discovered incidentally


Microscopic Pathology



  • Nodular lymphoid hyperplasia (nodular BALT hyperplasia)



    • Multiple coalescent enlarged follicles showing prominent germinal centers


    • Interfollicular lymphoplasmacytosis


  • Follicular bronchiolitis



    • Discrete accumulations of small lymphoid aggregates in peribronchiolar location


    • Sparing of alveolar septa by lymphoid infiltrates


  • Diffuse lymphoid (BALT) hyperplasia (diffuse interstitial pneumonia)



    • Predominantly interstitial proliferation of small lymphocytes distending alveolar septa


    • Process is generally bilateral and diffuse






Diffuse BALT hyperplasia of the lung shows massively distended alveolar septa occupied by a population of small lymphoid cells.






Higher magnification of diffuse BALT hyperplasia shows a dense population of small lymphoid cells abutting the respiratory lining mucosa image.


TERMINOLOGY


Synonyms



  • Pseudolymphoma, nodular lymphoid hyperplasia, lymphoid interstitial pneumonia


Definitions



  • Polyclonal proliferation of small lymphocytes arising within lung parenchyma


ETIOLOGY/PATHOGENESIS


Pathogenesis



  • Commonly associated with underlying autoimmune disorders such as Sjögren syndrome, rheumatoid arthritis, and collagen vascular diseases


  • Associated with viral infection, including HIV and Epstein-Barr virus


  • Associated with immunodeficiency, including common variable immunodeficiency, AIDS, and bone marrow transplants


  • Idiopathic


CLINICAL ISSUES


Epidemiology



  • Age



    • Adults 40-70 years of age (average = 50)


    • Diffuse form of the disease is more common in children


  • Gender



    • Female predilection


Presentation



  • Cough


  • Dyspnea


  • Asymptomatic; discovered incidentally


  • Dysproteinemia (hypergammaglobulinemia in 90% of patients)


  • May be associated with generalized lymphadenopathy or hepatosplenomegaly


Treatment



  • Surgical excision for localized lesions


  • Steroid therapy for diffuse lesions


Prognosis



  • Variable course depending on extent and progression of disease


  • Complete resolution is most common outcome


  • Diffuse cases may progress to end-stage pulmonary fibrosis with “honeycombing” of lung parenchyma


  • Diffuse cases may progress to diffuse lymphocytic lymphoma (MALT-lymphoma)


  • Death may ensue due to comorbid conditions, superinfection, or renal failure


IMAGE FINDINGS


General Features



  • Best diagnostic clue



    • Thin-walled cysts and centrilobular nodules


  • Location



    • Basilar interstitial thickening in adults with Sjögren syndrome


Radiographic Findings



  • Diffuse interstitial thickening, predominantly basilar


  • Multiple nodular pulmonary opacities, often with air bronchograms (more common in AIDS patients)


CT Findings

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Jul 9, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Pulmonary BALT Hyperplasia

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