Orbital Reticulum-cell Sarcoma: Report of Nine Cases.

RETICULUM-CELL sarcomata, together with leukaemia, Hodgkin's disease, giant follicular lymphoblastoma (Brill Symmer's disease), lymphosarcoma, and lymphoma, constitutes a group of lymphomatous or reticular tumours. These different lymphoblastomata appear to represent pleomorphism of the reticular system to unknown causal stimuli (Ginsburg, 1934; Gall and Mallory, 1942; Herbut, Miller, and Erf, 1945). The nomenclature of these tumours in the literature is confused, and identical lesions have been described by various writers as lymphomata, lymphoblastomata, lymphocytomata, malignant lymphomata, lymphosarcomata, reticular-cell type of lymphosarcomata, reticulo-sarcomata, and round-cell sarcomata. DukeElder (1952) states that: "reticulosarcoma of the orbit is not commonly noted in the literature, but it is probable that several cases have been described as lymphosarcomata. Its occasional occurrence is, however, undoubted (Wilson, 1940; McGavic, 1943)." Histological differentiation between lymphoid tumours and reticulum-cell tumours is often difficult, and both cell elements may participate in the formation of the same tumour (Pfanz, 1957). The histological structure may change in the course of the disease when a previously benign tumour becomes malignant. However, the various types of lymphomatous tumours may be differentiated by their clinical behaviour and by the nature of the cells and intercellular fibres constituting the tumour. Lymphomata are benign tumours composed of differentiated lymphocytes, but lymphosarcomata are highly invasive tumours. Their component cells are similar to lymphocytes, consisting of a mere rim of faintly stained cytoplasm and a relatively large nucleus with a dense chromatin network. The cells are closely and uniformly packed. Numerous mitotic figures are present. Lymphomata and lymphosarcomata may both be associated with leukaemia. Giant follicular lymphadenopathy is essentially a lymphocytic hyperplasia and may arise from several different causes. Reticulosarcoma cells are fairly large, and of varied shapes, round, polyhedral, oval, or irregular. Their cytoplasm is feebly stained, with a relatively