#How does the common type of tuberculosis cutis begin?#
The most common type of tuberculous ulceration or involvement of the skin usually results by extension from an underlying caseating and suppurating lymphatic gland; or it may have its origin as subcutaneous tubercles independently of these structures. It tends to spread, and may involve an area of one or several inches.
[Illustration: Fig. 48. Tuberculosis Verrucosa Cutis (Negro).]
#What are the clinical appearances and behavior of this type of tuberculous ulceration?#
It is usually superficial, has thin, red, undermined edges of a violaceous color, and an irregular base with granulations covered scantily with pus. As a rule, it spreads gradually as a simple ulceration, with but slight, if any, outlying infiltration. Subjective symptoms of a painful or troublesome character are rarely present. Its course is usually progressive but slow and chronic.
Other symptoms of tuberculosis are commonly to be found.
#Are other forms of tuberculosis cutis met with?#
A papulo-pustular eruption is sometimes observed, especially on the upper extremities and face; sluggish and chronic in character and leaving small pit-like scars; has been known as the _small pustular scrofuloderma_.
[Illustration: Fig. 49. Tuberculosis Verrucosa Cutis (patient had a coexistent pulmonary tuberculosis).]
An ulcerative papillomatous or verrucous tuberculosis of the skin (tuberculosis verrucosa cutis) is also occasionally noted, most commonly seated upon the lower leg or the back of the hand. It may be slight or extensive. Its mildest phase is the so-called verruca necrogenica.
Verruca necrogenica is a rare, localized, papillary or wart-like formation, occurring usually about the knuckles or other parts of the hand.
It begins, as a rule, as a small, papule-like growth, increasing gradually in area, and when well advanced appears as a pea, dime-sized or larger, somewhat inflammatory, elevated, flat, warty mass, with usually a tendency to slight pus-formation between the hypertrophied papillæ; the surface may be horny or it may be crusted. It tends to enlarge slowly and is usually persistent, but it at times undergoes involution.
[Illustration: Fig. 50. Tuberculosis Cutis (Verruca Necrogenica). (_After Model in Guy's Museum._)]