Once it is identified that granulomas present – epitheloid histiocytes and giant cells. (It may be helpful to identify the type of giant cells*). Assess whether there is necrosis and if so evidence of caseation. Are there neutrophils present to suggest suppuration? Assess the nodules. Typically sarcoidosis shows small well defined granulomas with no evidence of necrosis and may show Schaumann bodies (calcific concretions) and Asteroid bodies (have a fibrillary center) where as the nodules in TB are larger, more cohesive, poorly defined with caseating necrosis. Look particularly in areas of necrosis to identify if acid fast bacilli are present. Also assess for fungi such as aspergillus or evidence of foreign bodies such as suture material. (Polarise!). Consider doing a ZN, modified ZN and DPAS for TB & fungi.
Epitheloid granulomas with necrosis
- Caseating – Mycobacteriums tuberculosis, M avium intracellulare & M. lepra
- Non-caseating necrosis – Fungal
Non-necrotising granulomas (sarcoid-like)
- Lymph node draining carcinoma
Suppurative (Necrosis with neutrophils)
- Cat scratch disease (Bartonella Hensellae – stains on Warthin’s Starry Stain)
- Lymphogranuloma venereum (Chlamydia trachomatis)
*Types of giant cells
- 1) Touton giant cells – have a wreath like arrangement of peripheral nuclei with a peripheral clear rim of cytoplasm & a more eosinophilic central cytoplasm due to the high lipid content seen in xanthoma, xanthogranuloma & fat necrosis
- 2) Langhans giant cells- peripheral ring like nuclei with no peripheral clear rim of cytoplasm.
- 3) Foreign body – centrally located, overlapping nuclei.
N.B. There are no Langhans giant cells in Langerhans cell histiocytosis. Langerhans cells are dendritic cells with characteristic reniform nuclei found in the skin & mucosa containing Birbecks granules & stain positive for S100 & CD1a.
🙂 Paul Langerhans (1847-88) identified the insulin-producing cells of the pancreas (Islets of Langerhans) and the antigen-producing dendritic cells (now known as Langerhans cells) of the dermoepidermal junction. Theodor Langhans (1839-1915) was the first to describe the multinucleated cells now known as Langhans cells, characteristic of the granulomas in tuberculosis.
Diagnostic lymph node pathology. Wright et al. 2006.
Langerhans and Langhans: what’s misleading in a name?. The Lancet. Vol 362. Issue 9387. Pg 922. Sept 2003.