THE rarity of carcinoma of the jejunum cannot but have impressed itself on both the physician and the pathologist. The figures from the Mayo Clinic accentuate its infrequent occurrence : there, between 1921 and 1930, although 2513 cases of carcinoma of the stomach, and 2767 cases of carcinoma of the rectum were seen, no more than 8 cases of jejunal cancer came under observation ; and at the Vienna General Hospital the figures are even more striking, for in a series of 41,838 autopsies, although 8535 cases showed carcinoma, yet in only 8 cases was the small intestine the site of the growth.
Clearly certain factors, such as the alkaline reaction, the fluid nature, and the lack of stasis of the contents of the area, are responsible for preventing the spread of neoplastic tissue in the intestinal tract ; and the behaviour of pyloric carcinoma, which freely infiltrates the stomach wall, but almost invariably declines to affect the duodenum, supports the possibility that these factors may be causative in the rarity of jejunal cancer.
Malignant disease affecting the jejunum is of various types : lymphosarcomatosis, localized lymphosarcoma, leiomyosarcoma, myosarcoma, secondary carcinoma (from a primary focus in the ovary, uterus, or stomach)-all of them relatively more common than primary carcinoma, which latter may be differentiated as adenocarcinoma conforming to Broder's Class I or alternatively as of a comparatively undifferentiated type. The tumour tends to be polypoid in the younger patient, with resulting acute obstruction from intussusception. The usual form, however, is the slowly growing ring neoplasm of the scirrhous type, and this normally either ulcerates or undergoes colloid degeneration.
The condition frequently described as carcinoid tumour of the small intestine was formerly regarded as a basal-celled carcinoma (Johnson), but is now considered to be an argentaffin tumour, arising from the cells of Kulchitsky (Masson), or possibly a neurocytoma from the cells of Auerbach's plexus (Ehrlich).
The pathology of carcinoma of the jejunum could not be more tersely put than in the words of d'Allaines : " En general, l'epithtlioma du grile donne assez bien a la palpation la sensation que donne un petit ' bouton de Murphy ' place au niveau d'une anastomose ". " L'extension de l'ipithelioma est assez lente et pendant longtemps il reste confine aux territoires ganglionaires immediatement adjacent." And a recent communication from Dukes on carcinoma of the rectum, which emphasizes the lengthy interval before secondary glandular metastasis occurs in that disease, strikes a pleasing note of similarity with the words above.
CLINICAL ASPECT
The average age of the series of cases collected by Mayo and Nettrour, and in d'Allaines' series of About 200 cases in all have been recorded in the literature.