Pena-Shokeir type 1 syndrome with thymic and systemic lymphoid hyperplasia: Report of an autopsy case

We report a case of Pena-Shokeir type I syndrome in a female neonate who died of respiratory failure shortly after the birth at 32 weeks of gestation. In general appearance, she had apparent ocural hypertelorism, a depressed tip of the nose, low-set malformed ears, and microglossia in the head. There were severe contractures at the ankle, hand, fingers, and toes, and moderate contractures at the hip, shoulder, knee, and elbow. An autopsy analysis showed severe pulmonary hypoplasia and group atrophy of the skeletal muscle tissues. In addition to these findings which are well known characteristics of the infant with this syndrome, the thymus was markedly hyperplastic and lymph nodes were systemically swollen, especially the mesenteric ones which were visible and measured 2-5 mm in diameter. Histologically, the lymph nodes showed massive paracortical hyperplasia without apparent follicular structures, although no atypical lymphocytes were observed in both the thymus and lymph nodes. Immunohistochemically, proliferating lymphocytes seemed to be immature CD4+/CD8+ T cells, suggesting the insufficiency of T-cell negative selection in the thymus.