Tuberculosis cutis (overview) A18.4

Cook, 1882

Infection of the skin with Mycobacterium tuberculosis followed by the rarer triggers M.bovis and BCG bacillus (=attenuated M-bovis strain for vaccination) - see also Table 1.

• Exogenous: As a result of a primary or superinfection.
• Endogenous: Through lymphogenous or hematogenous spread.

Pathogen: Mycobacterium tuberculosis complex.

This includes the following species:

• (M.) tuberculosis (99%; human as reservoir)
• M. bovis (bovine tuberculosis)
• M. africanum (human as reservoir, see mycobacteria).

The following clinically cutaneous tuberculosis variants (see tuberculosis below) can be distinguished clinically and morphologically as entities:

• Tuberculosis cutis luposa (lupus vulgaris)
• Tuberculosis cutis colliquativa
• Tuberculosis cutis miliaris disseminata
• Tuberculosis cutis verrucosa (butcher's tubercle)
• Tuberculosis fungosa serpiginosa
• Tuberculosis ulcerosa mucosae et cutis
• Tuberculosis subcutanea et fistulosa
• Tuberculosis
  • Erythema induratum Bazin(nodular vasculitis)
  • Lichenoid cutaneous tuberculosis (tuberculosis cutis lichenoides)
  • Papulonecrotic tuberculid

An estimated 1/3 of humanity is infected with tuberculosis pathogens. Around 15% of those infected develop active tuberculosis. About 95% of cases and deaths occur in developing countries. In addition to the general nutritional status, the high HIV infestation is responsible for this.

The average incidence in Germany is 5.4/100,000 inhabitants/year. It is higher in various risk groups It is significantly higher in various risk groups (HIV-infected persons, immunosuppressed persons, drug addicts, malnourished persons, migrants from high-risk countries).

TB is the most common cause of death in AIDS patients. Multidrug-resistant tuberculosis (MDR = resistance to at least INH+RMP) is becoming an increasing problem (the number of infected people worldwide is estimated at 50 million). Countries with a high burden of MDR tuberculosis are (according to WHO, as of 2013: Belarus, Ethiopia, Armenia, Azerbaijan, Bangladesh, Bulgaria, China, Congo, Estonia, Georgia, India, Indonesia, Kazakhstan, Kyrgyzstan, Latvia, Lithuania, Moldova, Myanmar, Nigeria, Pakistan, Philippines, Russia, South Africa, Tajikistan, Ukraine, Uzbekistan, Vietnam). In the Philippines, the incidence in 2016 was 544 cases per 100,000 inhabitants (Veronese F et al. 2020).

Distribution patterns and prevalences of the different entities:

• Tuberculosis cutis colliquativa: relatively high prevalence in endemic areas of 50-70% - vs. 2.8% in non-endemic areas
• Tuberculous gums: 0%-13% of cutaneous tuberculosis; in malnourished or immunosuppressed patients
• Tuberculosis cutis luposa: the most common form of cutaneous tuberculosis in Europe (45-63%)
• Tuberculosis cutis verrucosa: 3%-19% of cutaneous tuberculosis, patients with good immunity
• Tuberculosis mucosae: 2.1% of cutaneous tuberculosis, patients with poor immunity
• Tuberculides
  • Erythema induratum Bazin (tuberculid): 18.7% -40% of cutaneous tuberculosis. Increased in Japan and China.
  • Lichenoid cutaneous tuberculosis: variable prevalence, 0.1% of cutaneous tuberculosis in Japan vs. 33% in India.

  • Papulonecrotic tuberculosis: 3%-12.8% of cutaneous tuberculosis. Mainly children and young adults.

The diagnosis of cutaneous tuberculosis includes immunological tests, direct pathogen detection methods, resistance tests and spread diagnostics (Gramminger C et al. 2025). Evidence is provided by pathogen detection in culture or PCR from biopsy material. In addition to pathogen detection, PCR can also be used to detect frequent resistance mutations. In multibacillary forms (in contrast to paucibacillary forms), pathogen detection is usually successful. Immediate isolation of the patient is necessary.

Histologically, the acid-fast rods can only be detected from a sufficient bacterial count, e.g. using Ziehl-Neelsen staining.

Immunological tests (tuberculin skin test or T-spot) show whether the organism has already immunologically dealt with tuberculosis. In the T-spot, lymphocytes circulating in the blood are incubated with antigens of the M-tuberculosis complex and the gamma interferon release is then measured.

In principle, the treatment of skin tuberculosis is identical to pulmonary tuberculosis. Here too, sensitivity testing is mandatory before initiating therapy. For adults, the recommended standard therapy remains unchanged, consisting of a combination of isoniazid, rifampicin, ethambutol and pyrazinamide for two months, followed by four months of further treatment with isoniazid and rifampicin. Regular monitoring of the most common side effects (hepatitis, neuritis, neuropathy, hyperuricemia, thrombocythemia) is required. The treatment regimen does not differentiate between tuberculosis or other cutaneous forms of tuberculosis. Successful treatment can be expected after 4-6 weeks, with complete healing of the lesion after 1-5 months.

Antibiotic resistance to tuberculosis is increasing worldwide. In Germany, the situation remains stable at a low level with a resistance rate of 5.7% in 2022 (Gramminger C et al. 2025).

Multidrug-resistant tuberculosis (MDR-TB), which is resistant to the two main drugs isoniazid and rifampicin, is of particular importance. Currently, at least six months of therapy with bedaquiline, pretomanid, linezolid and moxifloxacin (BPaLM regimen) is recommended for MDR TB. Monoresistance to rifampicin is treated in the same way as MDR-TBC.

Additional resistances include pre-XDR TB, which is resistant to isoniazid, rifampicin and fluoroquinolones, and XDR TB, which is also resistant to bedaquiline or linezolid.

For further details, see the respective clinical forms listed under definition below.

Cutaneous tuberculosis

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