Re‐infection (secondary) inoculation cutaneous tuberculosis
Authors: Sehgal Virendra N. , Srivastava Govind , Bajaj Promila , Sengal Ruchi 
Published: March 2003

Case 1 A 24‐year‐old crockery merchant reported on July 1, 1999 with a symptomatic, progressive, recalcitrant, reddish, noduloulcerative eruption on the left cheek. The patient was apparently well 3 months prior to reporting, when he suddenly experienced a mildly itchy raised eruption, probably following a (mosquito) bite. After scratching with the nail, he broke the continuity of the skin at the site. Since then the eruptions had increased in size, despite the use of antimicrobials (unknown). There was no recent history of cough/expectoration/evening rise in temperature or weight loss. Examination of the lesion was striking and was characterized by a noduloulcerative lesion (size, 2 × 2 cm). It was located on an erythematous brick‐red base. Marked induration was present (Fig. 1a). Apple‐jelly nodules were demonstrated on diascopy. A bacillus Calmette‐Guérin (BCG) vaccination scar was identified on the left deltoid. There was no regional lymphadenopathy, nor any systemic abnormality. A Mantoux test, with the intradermal injection of 0.1 mL SPAN's tuberculin (PPD/5 TU/0.1 mL), was negative after 72 h. Investigations, including total and differential leukocyte count, erythrocyte sedimentation rate, serum biochemistry, and renal and liver function tests, were normal, as was a chest X‐ray. Tuberculosis (TB) enzyme‐linked immunoabsorbent assay (ELISA) immunoglobulin M (IgM) antibodies (Ab): Mycobacterium tuberculosis IgM Ab titer was 0.5 (< 0.8: negative).

(a) A noduloulcerative lesion located on an erythematous brick‐red base. (b) Regression of the lesion after antitubercular therapy

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Hematoxylin and eosin‐stained sections prepared from the lesion showed multiple, well‐formed tubercles. Each tubercle consisted of epithelioid and giant cells and a peripheral zone of lymphocytes. Caseation necrosis was absent. A few plasma cells were also identified. The tubercles predominantly occupied the upper dermis, hugging the epidermis (Fig. 2). Secondary epidermal changes in the form of hyperkeratosis, acanthosis, and papillomatosis were observed. Tubercle bacilli could not be demonstrated. The diagnosis of lupus vulgaris was tenable; accordingly, conventional antitubercular therapy (ATT), comprising rifampicin 450 mg, isoniazid 300 mg, pyrazinamide 1500 mg, and ethambutol 800 mg, was administered. The last two drugs were withdrawn after 2 months, while the first two were continued for a 6‐month period. The response to the treatment was remarkable (Fig. 1b).

Multiple tubercles: each tubercle was formed by epithelioid, giant cells and a peripheral zone of lymphocytes (hematoxylin and eosin, × 100)

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Case 2 A 34‐year‐old business man presented with a symptom‐free, nonhealing plaque over the front of the right lower leg. It had appeared 8 months previously as a brownish black spot, and was associated with mild itching. The eruption did not progress for 3 months, after which it started to increase in size, acquiring its current position. Inadvertent trauma/injury to the area was not denied by the patient. A well‐circumscribed, raised, round, psoriasiform plaque of 2 cm in diameter was located over the anterior aspect of the right lower leg. The surface of the plaque was dry, rough, with elevated and depressed (miniature mountain) areas. Two fissures were also conspicuous. It was surrounded by an ‘‘erythematous halo’' (Fig. 3). Prompted by the preceding morphologic features, a diagnosis of tuberculosis verrucosa cutis (TBVC) was made and the patient was subjected to measurement of the total and differential leukocyte count, hemoglobin and erythrocyte sedimentation rate, kidney and liver function tests, and chest X‐ray: all were normal. A Mantoux test was negative. Mycobacterium tuberculosis IgM Ab titer was 0.3 (< 0.8: negative).

A well‐circumscribed, raised, round, psoriasiform plaque with a dry, rough, and fissured surface

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 Hematoxylin and eosin‐stained sections from the lesion revealed prominent changes confined to the epidermis in the form of marked hyperkeratosis, acanthosis, and papillomatosis. An acute inflammatory infiltrate comprising polymorphonuclear leukocytes and lymphocytes beneath the epidermis was also found (Fig. 4). Typical tubercles could not be located either in the mid or lower dermis. Tubercle bacilli were absent. The patient was given antitubercular treatment (ATT) (see above) and has since shown good improvement.

Marked hyperkeratosis, acanthosis, and papillomatosis, together with a collection of polymorphonuclear leukocytes and lymphocytes just below the epidermis (hematoxylin and eosin, × 100)

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