Differential Diagnosis of Melanoma Cells in Tissue Cultures of Uveal Melanomas

Introduction The differential diagnosis of melanoma cells in tissue cultures of uveal melanomas may present difficulties. Their growth patterns and morphological characteristics were reported in the preceding paper,1but since the morphology is not always clearcut, it was felt that the routine use of differential stains and histochemical reactions could be a valuable diagnostic adjunct. In an effort to determine what stains and histochemical reactions might best be suited to this purpose, a series of experiments was performed on melanoma cells from various sources. In addition to studies of variously stained preparations, a special study of the use of silver stains was undertaken. Of the many properties that have been used to identify melanin (color, site of formation, state of aggregation, mechanism of production, nature of the chromagen, solubility, chemical reactivity, composition), none is specific.2The most reliable of these differentiating properties, however, is chemical reactivity, i.e., the