B cell Chronic Intervillositis and Maternal Floor Infarction in a Placenta of a Stillbirth

Chronic histiocytic intervillositis with recurrence risk and perinatal adverse outcome is defined by the detection of maternal CD68-positive macrophages. Intervillous accumulation of B lymphocytes is a rare finding in miscarriage specimens and preterm and term placentas. However, there are case reports with manifestation of maternal B cell lymphoma. We present a case with focal brisk intervillous accumulation of CD20-positive lymphocytes in a placenta of a stillbirth from the 21st gestational week with additional maternal floor infarction and umbilical hypercoiling. Immunohistochemically, staining for CD3, CD5, CD10, and CD23 was negative in the intervillous lymphocytic population. Furthermore, neither clonal B cell-proliferation nor lymphoma were found in molecular pathological investigations. Clinical and/or histological signs of an infectious etiology were also not present. Accumulation of intervillous lymphocytes without clinical signs of infectious or neoplastic disease is probably a rare form of intervillositis due to a pathological immune reaction. The uncommon lesion may have contributed to the adverse outcome in this case.