Congenital langerhans cell histiocytosis with placental involvement.

Congenital presentations of Langerhans cell histiocytosis (LCH) are exceedingly rare, and concurrent placental parenchymal involvement has not been definitively documented in the literature. We present 2 cases of congenital multisystem LCH with placental involvement resembling chronic villitis. Placental examination may provide the initial diagnostic evidence of LCH and may significantly influence patient management and outcome; however, the prognostic implications remain unclear. In a clinical context suspicious for congenital LCH, the observation of chronic villitis should prompt consideration of placental involvement by LCH.

The pathogenesis of villitis of unknown etiology: analysis with a new conjoint immunohistochemistry-in situ hybridization procedure to identify specific maternal and fetal cells.

The conjoint immunohistochemistry-in situ hybridization (IHC-ISH) procedure permits, under routine light microscopic conditions, simultaneous documentation of either a male or female karyotype plus the immunological phenotype of individual cells within paraffin-embedded tissues. We have used this technique to characterize the inflammatory response in placental villitis of unknown etiology (VUE). A male placenta with severe VUE and appropriate control placentas were analyzed. In situ hybridization probes concurrently label both the X and Y chromosomes. On the same tissue section, individual cells were characterized with antibodies to CD3, CD68, or CD20. The amnion and syncytiotrophoblast were delineated by cytokeratin antibody (AE1/AE3). A complete karyotyping was performed on amnion cells to validate the procedure. Amnion cell karyotyping confirmed the accuracy of the procedure. The VUE case revealed that 88.8% of intravillous CD3+ lymphocytes were female (maternal), while 11.2% were male (fetal). Intervillous CD3+ lymphocytes and CD68+ macrophages were universally female. Intravillous CD68+ cells were only 10.5% female. Perivillous CD68+ cells were 94.6% female. Remarkably, multinucleated giant cells were exclusively maternal. This study confirms that lymphocytes in VUE are predominately but not exclusively maternal T cells. Our findings indicate that invasion of fetal villi by maternal T cells is associated with focal destruction of the syncytiotrophoblast, clarifying how placental immuno-defensive mechanisms may be contravened.