Intrathoracic Tumours of Carotid Body Type (Chemodectoma)

Intrathoracic tumours of carotid body type were identified by Lattes, who reported two cases in 1950. Since then only 10 further cases have been recorded, either because of their genuine rarity or from the infrequency of their recogni-tion. A more complete knowledge of the normal distribution of chemoreceptor tissue should result from a study of such neoplasms, and it is therefore of more than academic interest that these should be classified correctly. TERMINOLOGY Gaffney (1953), in describing jugular bulb tumours, suggested that their structure was prob-ably that of a chemoreceptor organ. Accepting LeCompte's (1948) view that tumours of the carotid body, which is the best defined and the most adequately studied of the chemoreceptor organs, reproduce in general the structure of the parent tissue, Gaffney further suggested that this group of neoplasms might be designated collec-tively by the term " receptoma." Mulligan (1950) described as a chemodectoma " a neoplasm consisting of chemoreceptor (chemo-dector) cells, which are associated with the distribution of parasympathetic nerves and which originate either in the adventitia of blood vessels in structures intimately connected with afferent nerve fibres or which occur along the branches or in the ganglia of the glossopharyngeal and vagus nerves. " Lattes and Waltner (1949) preferred " non-chromaffin paraganglioma, " the designa-tion " non-chromaffin " to distinguish this type of tumour from the paraganglioma of sympathetic nervous tissue. The term "paraganglion " had been used to include a number of diverse struc-tures ranging from the adrenal medulla to the glomus coccygeum, but, in 1950, Lattes clarified the position with the following classification. I True paraganglia (sympathetic) (a) Adrenal medulla (b) Chromaffin cell nests associated with the visceral sympathetic ganglia, especially along the thoraco-lumbar chain and the pelvic plexuses 11 Non-chromaffin paraganglia (parasympathetic) (a) Carotid and aortic arch bodies (b) Glomus jugulare (c) Ganglion nodosum of vagus (d) Ciliary body (e) Miscellaneous: other less constant mediastinal chemoreceptors, isolated groups in the retroperitoneal area, groin, and thigh III Carotid and aortic sinuses