Cutaneous Tuberculosis Occurring After a Skin Cut in a Child

Background. Tuberculosis is a common problem in Turkey, and cutaneous tuberculosis is a rare form of extrapulmonary tuberculosis. Herein, the authors describe a case of cutaneous tuberculosis (lupus vulgaris) occurring after contact with a sheep. Case. A 15-year-old boy was admitted to Marmara University School of Medicine Pendik Training and Research Hospital (Istanbul, Turkey) with delayed wound healing on the left index finger and left axillary lymphadenopathy. His medical history was unremarkable except for a wound incurred when he slaughtered a sheep 3 months before. One month after this injury, the patient developed enlargement of the left axillary lymph node on the side of the wounded extremity, and the wound turned a dark black color. The biopsy specimens obtained from the wounded skin and lymph nodes showed granulomatous reaction, but acid-fast bacilli (AFB) could not be shown with Ehrlich-Ziehl Neelsen staining. The patient tested positive in an interferon-gamma release assay. Computerized tomography scans of the thorax were normal, and early morning gastric lavage specimen was negative for AFB. The wound and axillary lymphadenopathy disappeared after institution of anti-tuberculosis therapy. Conclusion. Tuberculosis infection must be considered in chronic skin lesions with granulomatous reaction occurring in countries with high prevalence of tuberculosis.

Despite effective chemotherapy and strategic health programs, tuberculosis continues to be a common problem in Turkey. Tuberculosis in children is a major health problem worldwide, especially in developing countries. Therefore, 20% to 45% of the world’s population is infected with Mycobacterium tuberculosis and more than 90% of new cases occur in developing countries.¹ 

Cutaneous tuberculosis is a rare form of extrapulmonary tuberculosis and represents 1% to 2% of all cases of extrapulmonary tuberculosis.² Clinical manifestations of cutaneous tuberculosis vary from inflammatory papules to verrucous plaques, nodules, and chronic ulcers. Cutaneous tuberculosis is caused by M. tuberculosis complex including M. tuberculosis, M. bovis, M. africanum, M. microti, M. canetti, M. caprae, and M. pinnipedii, in the majority of the cases. Cutaneous lesions mostly develop by direct inoculation of tuberculosis bacilli from exogenous sources or hematogenous or lymphatic dissemination of the organism from endogenous foci.³ Primary cutaneous tuberculosis is caused by direct inoculation of tuberculosis bacilli into a traumatized area. Skin lesions caused by exogenous inoculation of microorganisms are usually characterized by painless papules, plaques, nodules, and indolent ulcers with regional lymphadenitis.³

This case report describes a case of cutaneous tuberculosis (lupus vulgaris) occurring after an injury while slaughtering a sheep. Written informed consent was obtained from the patient’s guardians for publication of this case report and any accompanying images. 

A 15-year-old boy was admitted to Marmara University School of Medicine Pendik Training and Research Hospital (Istanbul, Turkey) with a history of a persistent wound on the left index finger for the previous 3 months and left axillary lymphadenopathy. His medical history revealed he had accidentally injured his finger while slaughtering a sheep 3 months before presentation at the hospital. A painless, pruritic, erythematous papule had developed on the site of the injury 1 month after it was incurred, and the patient had a fever. The patient had later developed enlargement of the left axillary lymph node on the side of the wounded extremity. The wound remained unresponsive to antibiotherapy. The patient did not report night sweats, cough, weight loss, or any other constitutional symptoms. Physical examination revealed a 2 cm x 1 cm erythematous papule and shallow millimetric ulceration on his left index finger (Figure 1) and palpable axillar lymphadenopathy. He also had a Bacillus Calmette–Guérin (BCG) vaccine scar. Routine biochemical analysis and complete blood count all revealed normal findings. Erythrocyte sedimentation rate was 5 mm/hour and C-reactive protein was within normal ranges. Anti-human immunodeficiency virus antibodies were negative. Biopsy specimens were obtained from the skin and the lymph nodes. The skin biopsy showed superficial hyperkeratosis, granulomas without necrosis and caseation throughout the dermis, but no acid-fast bacilli (AFB) was observed with Ehrlich-Ziehl Neelsen (EZN) staining (Figure 2 A,B). Lymph node biopsy showed necrotizing granulomas without caseation reaction and reactive lymphoid hyperplasia. An interferon-gamma release assay (IGRA) was positive. There was no household contact. Computerized tomography scans of the thorax showed an enlarged lymph node at the right axillary region; however, there was no sign of pulmonary involvement. Early morning gastric lavage specimens were negative for AFB. Standard anti-tuberculosis therapy involving a 2-month period of isoniazid, pyrazinamide, rifampin, and ethambutol was initiated, followed by isoniazid and rifampin for 4 months. Clinically significant resolution was observed at 4 weeks after the initiation of therapy with healing of the wound without scar tissue formation and resolution of axillary lymphadenopathy.

Histologic examination of cutaneous tuberculosis shows granulomas with caseation necrosis and evidence of AFB; however, histopathologic findings are not specific in most cases. The diagnosis is often based on clinical manifestations as well as laboratory tests. Vashisht et al⁴ found clinical and histological concordance was 64% to 70%, AFB positivity was shown in 18.4% of the cases, and culture positivity for mycobacteria was observed in 10.7% of pediatric cases of cutaneous tuberculosis.⁴ Tissue culture is a gold standard method in establishing diagnosis and monitoring drug resistance.⁵ Tuberculosis bacilli can be easily detected in tissue specimens; however, few or no tuberculosis bacilli can be demonstrated, particularly in delayed presentations.² If few bacilli are observed in the tissue, central caseation necrosis may not accompany granulomatous reaction and bacilli may not be detected in tissue biopsies, so cultures may not yield M. tuberculosis.^6,7 Tuberculosis infection is a chronic granulomatous inflammatory reaction with central caseous necrosis; and although caseous necrosis is a hallmark feature of the infection, the absence of caseous necrosis does not rule out tuberculosis infection.⁸ The present patient did not show central caseation necrosis in biopsy specimens, nor did he show AFB with EZN staining.

The infections caused by primer inoculation of tuberculosis bacilli into the skin present with tuberculosis chancre, tuberculosis verruca cutis, or lupus vulgaris.⁹ Primer inoculation of tuberculosis bacilli into skin occurs through traumatized areas such as skin lacerations and ritual circumcision.^10-12 The lesion often appears as a painless nodule or indolent ulcer with regional lymphadenopathy occurring 3-8 weeks after skin lesions that are analogous to pulmonary Ghon complex.⁹ Cutaneous tuberculosis must be considered in differential diagnosis of such lesions. Fungal infections, sarcoidosis, syphilis, cat-scratch disease, and other diseases may be ruled out or differentiated by biopsy and culture. In the current patient, the authors performed skin punch biopsy. Due to the availability of only a small amount of specimen, mycobacterial and bacterial cultures were not possible.

The information regarding the efficacy of the BCG vaccine in protecting against cutaneous tuberculosis is controversial and variable. Clinical studies^13,14 reported BCG vaccine protects against meningitis and miliary tuberculosis; however, several studies have failed to show efficacy for the BCG vaccine to prevent cutaneous tuberculosis.¹⁵ Kumar et al⁸ showed no disseminated disease in a group of BCG-vaccinated patients with cutaneous tuberculosis; however, 9.7% of children in the unvaccinated group had disseminated disease.⁸

The treatment of cutaneous tuberculosis is the same as in systemic tuberculosis, and clinical response is observed approximately within 3 weeks.⁴ In the presence of a strong clinical suspicion for cutaneous tuberculosis in cases that could not be confirmed by laboratory tests or biopsy, the diagnosis can be based on the response of the lesion to anti-tuberculosis therapy. In the present case, cutaneous tuberculosis was diagnosed based on the presence of granulomatous reaction in biopsy specimens and a positive IGRA test. Excellent response to treatment and resolution of the lesion supported this diagnosis. 

In conclusion, tuberculosis infection must be considered in chronic skin lesions with granulomatous reaction occurring in countries with a high prevalence of tuberculosis. 

Affiliations: Division of Pediatric Infectious Diseases, Department of Pediatrics, Marmara University School of Medicine, Istanbul, Turkey; and the Department of Pathology, Marmara University School of Medicine

Correspondence:
Ahmet Soysal, Prof, MD
Fevzi Çakmak Mah.
Mimar Sinan Cad.
Pendik, Istanbul, Turkey
asoysal@marmara.edu.tr

Disclosure: The authors disclose no financial or other conflicts of interest.