Cutaneous tuberculosis: epidemiological, clinical, diagnostic and therapeutic update

Abstract

Tuberculosis is certainly one of the diseases considered to be ancient on planet Earth. The etiological agent of tuberculosis is Mycobacterium tuberculosis. This terrible bacterial infection still results in severe socioeconomic consequences to date, and its complete eradication represents a great challenge. It constitutes one of the most important public health problems in developing countries. According to the World Health Organization, this infection results in more than 4,000 deaths daily worldwide, with 10.4 million being affected annually and 1.5 million deaths from TB every year. With the emergence of the HIV/AIDS pandemic, the disease became the main cause of morbidity and mortality in patients infected with the human immunodeficiency virus. Cutaneous tuberculosis is a rare infection that represents 1% to 1.5% of extrapulmonary tuberculosis, whose etiological agents are Mycobacterium tuberculosis, Mycobacterium bovis, and the attenuated form of the bacillus Calmette-Guérin (BCG vaccine). Cutaneous tuberculosis can be exogenous; endogenous: caused by contiguity or autoinoculation and by hematogenous spread; induced by the Calmette-Guérin bacillus and manifest as a tuberculid. The diagnosis of the infection is carried out through the direct test, culture, histopathology, tuberculin skin test, polymerase chain reaction, interferon-gamma release assay, and genotyping. Drugs used comprise isoniazid, rifampicin, pyrazinamide and ethambutol.

Keywords: Epidemiology; Mycobacterium tuberculosis; Pathogenesis, homeopathic; Tuberculosis; Tuberculosis, cutaneous.

Figure 1

(A), Tuberculosis verrucosa cutis (TVC): verrucous plaque with centrifugal expansion on the left arm. (B), TVC: epidermis with focal hyperplasia and dermis showing granulomatous inflammation involving follicular structures and vessels, (Hematoxylin & eosin, ×40).

Figure 2

(A), Scrofuloderma – nodules/gummas and ulcerations on the cervical and right mastoid regions associated with lymph node tuberculosis. (B), Scrofuloderma – infiltrated and ulcerated lesions on the right clavicular region. (C), Scrofuloderma – caseation necrosis surrounded by granulomatous inflammation with a palisade of macrophages and Langhans-type multinucleated giant cells, (Hematoxylin & eosin, ×40).

Figure 3

(A), Tuberculosis orificialis (tuberculosis cutis orificialis) – Ulcerovegetating lesion affecting the labia majora and minora. (B), TB orificialis – ulcerated epidermis and massive dermal granulomatous inflammatory infiltrate, (Hematoxylin & eosin, ×40). (C), TB orificialis – granuloma associated with caseation necrosis, (Hematoxylin & eosin, ×200). Pictures by: Dr. Maraya Bittencourt.

Figure 4

(A), Lupus vulgaris – infiltrated, eroded lesion, with sharp edges, in the right masseteric region. (B), Lupus vulgaris – extensive plaque covered with papules/nodules, scarring areas, with sharp raised edges on the right gluteal region. (C), Lupus vulgaris – the dermis shows granulomatous inflammation with foci of caseous necrosis, (Hematoxylin & eosin, ×40).

Figure 5

(A), Gummatous TB – irregular ulcer with sharp edges on the cervical region. (B), Gummatous TB – granuloma consisting of lymphocytes, macrophages and multinucleated giant cells, (Hematoxylin & eosin, ×100).

Figure 6

(A), Sporotrichoid gummatous TB – ulcerated lesions along the upper limb. (B), Sporotrichoid gummatous TB - numerous resistant acid-fast bacilli (AFB) in the infiltrate on Fite-Faraco staining. Pictures by: Dr. Deborah Unger.

Figure 7

Post-BCG TVC – disseminated annular lesions on the trunk and upper limbs.

Figure 8

(A), Papulonecrotic tuberculid – “punched-out” lesions on the lower limbs. (B), Papulonecrotic tuberculid – papuloerythematous and papulocrustous lesions in the lower limbs. (C), Papulonecrotic tuberculid – thinning of the epidermis and granulomas with caseation necrosis in the underlying dermis, (Hematoxylin & eosin, ×20).

Figure 9

(A), Erythema induratum of Bazin – erythematous-violaceous infiltrated nodule on the posterior aspect of the lower limb. (B), Erythema induratum of Bazin – Lobular granulomatous panniculitis. (C), Erythema induratum of Bazin: Strong reaction to PPD skin test.