The Poster 

This poster was created for the busy diagnostician in an effort to bridge the gap that exists between the data source (the pathology microscopic image) and the differential diagnostic possibilities.  The process defined in this work is algorithmic and entails a winnowing of diagnostic possibilities that derive from 6 major morphologic patterns, identifiable at scanning magnification on the light microscope. Each pattern is further subdivided according to additional specific observed findings.  The method does not always result in one specific diagnosis, but rather ends with a narrow differential diagnosis that can be resolved with the addition of clinical and radiologic findings. Each disease or condition in the differential diagnosis is discussed at length in the textbook entitled Practical Pulmonary Pathology A Diagnostic Approach (www.elsevierscience.com).

Inevitably some overlap occurs between patterns and this too can be a useful guide to the correct diagnosis.  For example, some infections are both nodular and have airspace filling (e.g. botyromycosis, aspiration pneumonia), while others are characterized by acute lung injury and diffuse airspace filling (e.g. pneumococcal pneumonia, pneumocystis pneumonia.)  In fact, for some diffuse inflammatory conditions in the lung, all 6 patterns may be present in different areas of the same biopsy (e.g. rheumatoid lung).

In practice, recognizing the dominant pattern is essential to navigating the differential diagnosis addressing the primary clinical concerns, and it is important to note that certain patterns are dominant over others based on clinical concerns.  Acute lung injury (Pattern 1) always trumps other patterns, given the acuity of the clinical presentation and potentially lethal immediate consequences (e.g. “Diffuse alveolar damage, with scattered granulomas; or fibrosis; or vasculitis; etc”).  Fortunately, the poster is designed to allow the user to arrive at the correct differential diagnosis almost regardless of initial pattern chosen.

The successful pathology diagnosis for the diffuse non-neoplastic lung diseases is often descriptive of the pattern and inclusive of a differential diagnosis in order of decreasing likelihood.  For each pattern and its differentiating elements, a sample diagnosis is included as a working template.  It is essential for the diagnostic pathologist to remember that these non-neoplastic diseases and conditions are significantly effected by information often not available at the time of diagnosis.