This local form of cutaneous tuberculosis may be considered under two headings.
Verruca necrogenica (postmortem wart, anatomical tubercle) is the simpler and more usual type of this uncommon tuberculid. It occurs chiefly on the knuckles or other parts of the hands of persons who are in the habit of handling dead tissue containing live bacteria, hence it is encountered chiefly among physicians, medical students, dissecting-room and hospital attendants, and butchers. It begins as a small papule which increases slowly in area and finally becomes a dime-sized or larger, inflamed, elevated, flattened and warty nodule. Pus may form between the papillary excrescences, in which case there may be a crust covering the growth or it may retain its hard, warty appearance. There is a tendency toward central healing and peripheral spreading, although the growth rarely exceeds an inch in diameter. It is usually benign in its character although rarely lymphatic involvement and constitutional infection has been noted.
Fig. 130 – Tuberculosis verrucosa, the variety known as verruca necrogenica, in a hospital attendant. Cured by a mercuric chlorid solution and the X-rays.
Tuberculosis verrucosa cutis (of Riehl and Paltauf) may start in a small insignificant lesion like the variety just mentioned, but eventually it becomes much more extensive from the coalescence of one or more patches, forming an irregular-shaped serpiginous lesion. It is typically seen on the back of the hand but may be found anywhere on the arms or legs. The lesions may be brown, dull or purplish-red in color and present a warty surface, although some small discrete pustules may be seen closely aggregated on the inflamed area. A purulent or seropurulent fluid is frequently noted between the papillary elevations. this form is found in the same class of persons as the first variety.
The duration of tuberculosis verrucosa is variable. Spontaneous evolution may take place with a regular scar. Often the growths are overlooked because of their small size, stationary character and slight annoyance.
Etiology and Pathology. – The predisposition afforded by certain occupations has been mentioned and, together with the direct inoculation of some wound of the surface with the tubercle bacillus, constitutes an efficient etiology. No constitutional predisposition is necessary, and it has been observed that most of the cases are in good bodily condition. The reaction of the dermal tissue to the presence of the bacillus causing epithelial and papillary hypertrophy, is a common pathological change found in warty tuberculosis. Systemic infection, involving the lymph glands and viscera, is a possible occurrence. The tissue environments of the bacillus in this type of the disease are responsible for its close limitation to the epidermis or to the upper layer of the cutis. The bacilli are more superficially situated than in the other forms but are less abundant than in the orificial type and yet more numerous than in lupus.
Fig. 131 – Tuberculosis verrucosa, the variety known as tuberculosis verrucosa cutis. These lesions bear a close resemblance to blastomycosis but the tubercle bacillus was easily found. Cured by the X-rays and applications of pyrogallol.
Diagnosis. – It may be necessary to differentiate simple verruca but the occupation of the one infected, the mode of occurrence and inflammatory pustular lesions should distinguish the anatomical wart. Blasto-mycosis may resemble the more extensive form of warty tuberculosis and a microscopic examination will be necessary to discover the blasto-myces. the discovery of the tubercle bacillus is pathognomonic but failure to find it is common and of slight negative value.
Prognosis of the local condition is most satisfactory inasmuch as all of these lesions can be completely obliterated.