Pulmonary neuroendocrine cell distribution in sudden infant death syndrome

The density of pulmonary neuroendocrine cells (PNECs) in 21 sudden infant death syndrome (SIDS) cases, 19 controls, and 25 fetuses was studied morphometrically. Formalin-fixed, paraffin-embedded lung samples were immunostained with antibody against chromogranin A (CGA). The percentage of PNEC-positive airways and the density of PNECs in each airway were calculated in all cases. The density of PNECs was expressed as the number of cells per millimeter of basement membrane. The percentage of PNEC-positive airways reached nearly 100% by term and did not change significantly until 12 months of age in both the SIDS cases and the controls. The density of PNECs also showed a rapid increase in the saccular stage fetus and had its peak of about 4 cells/mm around birth. The density of PNECs, including the standard deviation, was higher in SIDS cases than in controls. The uneven distribution of PNECs may affect respiratory control in SIDS victims.