Histo-Pathological Study of the Temporal Bone in Leprosy

Abstract

This repot is on a histopathological investigation of the temporal bones of six lepromatous leprosy patients of long standing. Exterial and radiological examination in leprosy revealed no clinical changes in any of the six patients, none of whow had had a past anamnesis of ear diseases which frequently bring temporal bone changes.
1. Bone Changes
There was no leprom, round cell infiltration or mycobacterium leprae. However, absorption of bone tissues, lacunal arrosion, dilatations of the Haversian canal, rarefying, halisteresis and osteoprosis were found.
2. Vascular Changes
In all cases, considerable changes in the vascular system of the temporal bone were found as follows: (a) Blood capillaries in the bone tissues were filled up with hyaline and fibrinoideal substances. (b) Distinction between the tunica interna, the tunica media and the tunica externa had become vague due to hypertrophic intima, an increase in endothelial cells, hyaline degeneration and an infiltration of small round cells into the vascular wall. (c) In 2 cases, granular acid fest bacilli dotted the muscular walls of the arterioles. (d) In addition, fibrinoid degeneration, especially of the tunica media and the tunica externa was externaly advanced. This latter phenomenon never been clearly described in the literature on the leprous vasculitis.
Since in recent times, much emphasis has been laid on a correlation between this fibrinoid degeneration and allergic vasculitis, I would interpret this fibrinoid degeneration as a sign of leprous allergy. This histopathological investigation leads me to conclude that vascular changes in the temporal bone are very important causes of nonspecific bone changes in leprosy, although it is the vasomotor nerve disturbances which have been thought to be most significant cause.
3. Peripheral nerve changes
(a) The intistitial tissue around the bundle of nerve fibres had increased, especially in case No.5. (b) A slight disbundling of the medullated nerve and a partial demyelin phenomenon were observed. (c) Infiltration of the small round cells around some of the nerve bundles had occuered in two cases. (d) An increase in arterial intima around the nerve fibre bundles was slso observed. I interest these changes, especially the arterial changes, to be the fundamental causes of those in the nerve and the bone tissues.
4. Other soft tissue changes
The pathological findings in the bony Eustachian tube, tympanic menbrane, tympanic cavity, internal ear and cellular endosteum were as follows: (a) No one in the bony Eustachian tube and internal ear. (b) Hypertrophic endosteum, edema and round cell infiltration into the cellular endosteum were found in 4 cases. (c) Round cell infiltration and degenerated leprosy like bacilli in the tympanic mucous menbrane were found in only one case.