Custom Search



Infectious Disease Online

Pathology of Primary Atypical Pneumonia

Dr Sampurna Roy MD                        




Atypical pneumonia is a pneumonia that does not respond to the usual antibiotic treatment.

The organisms may cause clinical and pathological patterns ranging from mild upper respiratory infection (common cold) to severe lower respiratory tract disease.


It can be caused by bacteria, in particular Mycoplasma pneumonia , Legionella pneumophila,  and Chlamydophila pneumoniae.

Other organisms include Chlamydia psittaci (Psittacosis), Francisella tularensis (tularemia), and Coxiella burnetii (Q Fever).

Viruses include influenza A or B, respiratory syncytial virus infection, adenovirus, rhino virus, herpes simplex and cytomegalovirus infection. 

Severe acute respiratory syndrome (SARS) virus, is a new coronavirus that causes atypical pneumonia.


1. Patchy or lobar areas of congestion without consolidation hence called atypical pneumonia.

2. Predominance of interstitial pneumonitis with widened edematous alveolar wall containing mononuclear inflammatory cells.

3. Formation of hyaline membrane due to diffuse alveolar damage.

Superimposed bacterial infection is common.

In severe infection, necrosis of bronchial or alveolar epithelium is seen in Herpes simplex, adenovirus and varicella.

Characteristic nuclear inclusion is seen in Cytomegalovirus infection


Further reading:

Pathologic Aspects of Atypical Pneumonias

Community-acquired pneumonia: an unfinished battle.

Severe community-acquired pneumonia caused by macrolide-resistant Mycoplasma pneumoniae in a 6-year-old boy.

A trigger enzyme in Mycoplasma pneumoniae: impact of the glycerophosphodiesterase GlpQ on virulence and gene expression.

Amplification of 16S rDNA by nested PCR for measurement of Mycoplasma pneumoniae DNA over time: clinical application.




Dr Sampurna Roy  MD

Consultant  Histopathologist (Kolkata - India)



  ;  Dermpath-India  ;   Soft Tissue Tumour Online ; Cardiac Path Online ;

Infectious Disease Online ;  Paraganglioma-Online Mesothelioma-Online ; Pathology Quiz Online ;

GI Path Online ; Pulmonary Pathology Online  ; Lung Tumour Online ; Endocrine Pathology Online ;

Ear Pathology Online ;   Eye Pathology Online ; Paediatric Pathology Online ;

E-book - History of Medicine ; Microscope - Seeing the Unseen





Privacy Policy  

Advertising Policy

Copyright 2020