In the ordinary course of the disease the macular eruptions disappear, and the neuritic symptoms—anæsthesia, muscular paralysis and atrophy, and necrosis of bone—appear. Sometimes, though rarely, there are several macular eruptions after the disappearance of the earlier maculæ, or there may be an eruption of nodules. If, then, these eruptions are auto-infections, they are evidence in favour of the unity of the disease, in spite of the difference in form.
Where the bacilli come from, in these, so to speak, later eruptions, when there is no skin affection, it is difficult to say with certainty. In a case of maculo-anæsthetic leprosy we found the inguinal glands leprous, although no skin eruption was present. Possibly, then, fresh eruptions develop from the glands when the original skin eruption has disappeared. Thus the specific leprous affections gradually disappear, and only their results remain—in other words, the leprosy is healed. Most maculo-anæsthetic patients become in time purely anæsthetic; they no longer suffer from leprosy, but only from its results. The late eruptions show, however, how difficult it is to define the fact of recovery, for when all externally diagnosable signs of actual leprosy are gone, bacilli may still remain somewhere in the body, in the lymphatics, or possibly in the liver and spleen.
Chapter V.
PATHOLOGICAL ANATOMY OF THE MACULO-ANÆSTHETIC FORM.
The maculæ exhibit generally the same anatomical characters as do the nodular lepromata, viz., infiltrations with round cells, epithelioid and spindle cells. The difference between them is quantitative; in the macular infiltration the number of bacilli are less. We will describe the microscopical appearance of macules of different duration.
In a recent (three weeks old) macule, microscopical examination showed cord-like and rounded infiltrations of the cutis, with round and epithelioid cells, mostly arranged around the vessels. There were pretty numerous bacilli lying between and also definitely in, the cells; here and there were found little collections of bacilli or bacillary granules, with one or more nuclei—small globi—in their neighbourhood, which in size could not be compared with those found in the tuberous form. Specimens hardened in perosmic acid showed unaffected nerve fibres, which the leprous infiltrations did not implicate. Gold preparations showed a marked increase in the number of Langerhans’ cells in the epidermis, which, indeed, we expected, since we agree with Ranvier in considering them as wandering cells, and not as nervous elements. Definite changes in the cutaneous nerves were not evident.
Microscopical sections from an older spot (perhaps two years old) show here and there infiltrations in the cutis—especially around the vessels, consisting of epithelioid, round and spindle cells. Bacilli were found here and there—one or two in each infiltration. In the lumen of one small vessel we found a collection of round cells, with a bacillus among them; and on the inner side of the wall of another vessel we saw a similar appearance. Gold preparations of this macule, which was definitely anæsthetic, showed slight changes in the small nerve twigs in the cutis, less marked precipitation of the gold salt in the nerve fibres, and a number of Langerhans’ cells.
Sections from a very old anæsthetic macule showed only very slight infiltration along the vessels; the cells were mostly spindle-shaped; only a few were round or epithelioid. In most of the sections no bacilli were found; in some, one or two distinct bacilli and some granules, taking the same stain.
The maculæ are therefore like the nodules, leprous infiltrations of the cutis, consisting of round epithelioid and spindle cells, the latter being more numerous the greater the age of the macule. These infiltrations appear to proceed from the vessels. Lepra bacilli are always present, but are most numerous in the younger macules. In young, not as yet anæsthetic, macules, the nerve twigs appear unchanged; in the older ones they are usually affected. Langerhans’ cells are, according to our view, wandering cells, and their number is probably dependant on the inflammation.
We have only had the opportunity of examining the nerves in this form of the disease in old cases, and have not found bacilli in them, but merely great increase of the interstitial connective tissue and disappearance of the nerve fibres. Dr. Arning has, however, as is well known, found bacilli in a piece of ulnar nerve which he removed during life from an anæsthetic patient. Our results, therefore, correspond with the proposition put forward above, that the leprous affection disappears, and that the anæsthesia is a result of the atrophy of the nerves caused by secondary shrinking. We found on a mutilated finger the collateral nerve almost completely transformed into fibrous tissue, not a single medullary fibre being evident. In a case where on account of joint disease (which proved to be tubercular) we amputated, the small periosteal nerve twigs were much degenerated; in another, where the foot was amputated for gangrene, the small peri-articular nerves also showed degeneration.
Danielssen found, in some cases, changes in the spinal cord which, using the methods of investigation then at his disposal, he regarded as degenerations and inflammations of leprous origin.