DNA ploidy in clinical malignant gastric lesions less than 5 mm in diameter.

Nuclear DNA content was microspectrophotometrically measured in 18 patients with a mucosal carcinoma of the stomach less than 5 mm in diameter. The findings were compared with data on 56 patients with a lesion greater than 5 mm. DNA distribution patterns were grouped into low and high ploidies. A mucosal carcinoma, classed as high ploidy, was confirmed in 27.8%, 22.2%, and 28.9% of the lesions with a diameter of less than 5 mm, 5 to 20 mm, and 20 to 40 mm, respectively. In the high-ploidy group with a lesion exceeding 5 mm, there was a preponderance of an elevated lesion, well- and moderately differentiated adenocarcinomas, and location in the lower third of the stomach. Such pathologic features showed the same tendency in the high-ploidy group with a lesion less than 5 mm. An aneuploid carcinoma may be present even in a lesion confined to the mucosa, and less than 5 mm in diameter.