Sarcoidosis

Fully developed

Collection of epithelioid histiocytes throughout the dermis and sometimes throughout lobules of the subcutaneous fat; granulomas usually discrete, but my be confluent
Tiny focus of necrobiosis in the center of collections of histiocytes sometimes
Multinucleate histiocytes sometimes present within the granulomas
Inclusion, i.e., asteroid bodies(eosinophilic star shaped bodies) or Schaumann bodies (basophilic laminated concentric whorls) sometimes observed within some histiocytes, neither of the specific
Few or no lymphocytes at the periphery of collections of epithelioid histiocytes; granulomas at times, however, surrounded by numerous lymphocytes, especially in lobules in the subcutaneous fat

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Histopathological diffrential diagnosis

  1. Silica granuloma: presence of crystalline particles within histiocytes
  2. Lichen nitidus