Mucin histochemistry of the developing gastroesophageal junction.

Mucin histochemistry was performed on the squamocolumnar junction (Z-line) of the gastroesophageal region of 49 autopsied previable fetuses, stillbirths, infants, and young children, using alcian blue pH 2.5/periodic acid-Schiff (PAS) and alcian blue pH 1.0/PAS stains. Sialylated and neutral mucins were present in most and sulfated mucin in many cases. In only one fetus was a heterotopic focus of goblet cells found in the distal esophagus. This study confirms that the presence of acidic mucins in columnar epithelium, without goblet cells, at the Z-line and adjacent cardia is common in this age group. Undue reliance on mucin stains to identify metaplastic columnar epithelium, in the absence of goblet cells, may result in overdiagnosis of Barrett's esophagus in children.