Langerhans cell histiocytosis

Langerhans cell histiocytosis, abbreviated LCH, is a rare genetic disorder of tissue macrophages. It broadly fits into the category of histiocytoses. It used to known as eosinophilic granuloma. It has been referred to by several eponyms - Hand-Schüller-Christian disease, Abt-Letterer-Siwe disease, and histiocytosis X.

General

• Looks like pulmonary Langerhans cell histiocytosis - see medical lung diseases.

Microscopic

Features:

• Langerhans cells histiocytes - key feature.
  • Clusters of cells (histiocytes) with a reniform (kidney-shaped) nucleus and abundant foamy cytoplasm.
    • Nucleus may look like a "coffee bean", i.e. have nuclear grooves (similar to those in papillary thyroid carcinoma) -- appearance dependent on the rotation of the nucleus.
    • Chromatin pattern: fine granular, light gray.
• +/-Eosinophils - often prominent.

Images:

• LCH - lymph node - very high mag. (WC).
• LCH - lymph node - high mag. (WC).

DDx:

• Kimura disease - eosinophilia.
• See lymph node pathology.

IHC

• CD1a +ve.
• S100 +ve.
• CD207 (AKA Langerin) +ve.

Electron microscopy

• Birbeck granules.

Etiology:

• Cell membrane invagination.

Appearance:

• Electron dense, cytoplasmic tennis racket-like body.

Images:

• LCH (upmc.edu).

See also

• Lymph node pathology.
• Histiocytoses.