MATERIALS AND METHODS

The cases included 3 malignant histiocytomas and 4 fibrous xanthomas, 1 of which was questionably malignant. All of them were treated and studied at Columbia-Presbyterian Medical Center, New York, NY The tissues were fixed either in Zenker’s acetic or in Bouin’s solution and stained with hematoxylin and eosin. Special stains included the Laidlaw’s method for reticulin and the Heidenhain’s “azan” modification of Mallory’s connective tissue stain. In some cases, tissue fixed in neutral Formalin (10% aqueous solution) was stained with Sudan IV. The Maximow double-coverslip, lying-drop method of cultivation was used. 28 The tissue fragments were explanted into a chicken plasma clot and fed with a nutrient solution consisting of human placental serum, beef serum ultrafiltrate, and a 50% saline extract of 9-day chick embryo. Some cultures of 1 histiocytoma and of 1 fibrous xanthoma were exposed to intravital staining with lithium carmine while those of another fibrous xanthoma were stained supravitally with neutral red. The cultures were stained at various intervals with Jenner-Giemsa, by Bodian’s Protargol method, by Masson’s trichrome method, with Delafield’s hematoxylin, or were mounted unstained for phase microscopy. The time of cultivation was protracted up to 38 days.