Table of Contents

Washington University Experience | NEOPLASMS (HEMATOLYMPHOID) | Langerhans Cell Histiocytosis (LCH) | 9G2 LCH (Gaegel's Granuloma) (Case 9) ISH Lambda

In situ hybridization (ISH) shows an approximately 2:1 ratio of kappa-light chain to lambda-light chain (9G2) restriction, suggesting a non-clonal origin for these cells. ---- Comment This microscopic pattern is diagnostic of Langerhans cell histiocytosis (LCH). Given the clinical and histomorphological features of this case, we also considered a diagnosis of lymphocytic hypophysitis (LH); however, the presence of CD1a positive cells, considered a highly specific marker for Langerhans histiocytes, is not a feature of LH. Furthermore, involvement of the optic nerves/chiasm and sparing of the pituitary are far more consistent with LCH than with LH. Historically, involvement of the hypothalamus by LCH has been referred to as Gagel's granuloma, hypothalamic granuloma, or Ayala disease. In the setting of concomitant bone involvement, it was also considered a component of Hand-Schuller-Christian disease. Langerhans cell histiocytosis is now the preferred term for this group of neoplasms.

---