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Indian Journal of Medical Microbiology, Vol. 30, No. 1, January-March, 2012, pp. 98-100 Case Report Primary inoculation tuberculosis following a vehicular accident S Zadbuke, N Khan, R Set, J Shastri Department of Microbiology, TNMC, Mumbai - 400 008, India Correspondence Address: Date of Acceptance: 30-Sep-2011 Code Number: mb12020 PMID: 22361771 DOI: 10.4103/0255-0857.93058 Abstract Tuberculosis is considered as a 're emerging disease', because of its resurgence and increased incidence in the 21 st century particularly in immuno-compromised patients. About one fifth of diagnosed new cases of tuberculosis have an extrapulmonary lesion, of which about one-tenth involve the musculoskeletal system. Tuberculosis involving the soft tissue from adjacent bone or joint is well recognized but cutaneous tuberculous infection is rare, accounting for 0.1% of all cases seen in a dermatology service. We report a case of primary cutaneous tuberculosis of forearm following a vehicular accident in a young immunocompetent female. Keywords: Cutaneous tuberculosis, forearm, immunocompetent Introduction Primary skin tuberculosis (TB) is an old infection, first described by pathologists as the prosector′s wart. Although the disease was thought to be a predominantly occupational disease, it is being encountered more frequently in healthy individuals where the source of infection remains in most cases unidentified. [1] In areas such as India or China where TB prevalence is high, cutaneous manifestations of TB (overt infection or tuberculids) are found in less than 0.1% of individuals seen in dermatology clinics. [2] Primary cutaneous TB following a vehicular accidental wound could not be found on extensive literature search. Hence, we report a case of primary cutaneous TB resulting from vehicular accidental trauma to forearm in an immunocompetent young female patient. Case Report A 20-year-old female, a security guard by occupation, resident of Malvan, Maharashtra, presented with a irregular plaque on the anterior aspect of left elbow with scarring and pus discharge since 4 years. The patient had suffered a road traffic accident 4 years back when she sustained injury on left elbow with tissue loss which healed on its own. After 1 year, she developed swelling with uneven scarring and occasional pus discharge on the same site. The patient was treated conservatively with Clotrimazole. There was some decrease in the discharge but the lesion did not heal completely. She complained of episodic fever but no cough, haemoptysis, weight loss, or close contact with any known case of TB. She had a history of jaundice 5 years back and three blood transfusions during the same illness. There was no past history of tuberculosis. Physical examination of the lesion showed a single ill-defined approximately 8 x 6 cm irregular, firm, nodular, erythematous plaque on anterolateral aspect of left elbow [Figure - 1]. There was scarring with hypopigmentation and surrounding hyperpigmentation with multiple overlying scaly papules with serosanguinous and purulent discharge. No regional lymphadenopathy could be detected. All range of movements at elbow, wrist and finger joints were normal. Routine investigations were within normal limits. Serum HIV and VDRL were non-reactive. Chest X-ray and left elbow X-ray were within normal limits. A skin biopsy was done and the tissue was sent for bacterial, mycobacteriological and fungal culture in suspicion of Atypical Mycobacteria, Actinomycetes and Chromoblastomycosis. Cultures for bacteria, Actinomycosis and fungi were negative. Primary smear for AFB stained by the Ziehl-Neelsen staining procedure was negative. Histopathology of the biopsy revealed epithelioid cell granuloma and lymphocyte infiltration in the epidermis [Figure - 2]. Culture of the biopsy on Lowenstein-Jensen media grew rough, yellowish colonies after 4 weeks. On speciation it was confirmed to be Mycobacterium tuberculosis. Drug sensitivity for isoniazid and rifampicin was performed by economic variant of proportion agar method and strain was found sensitive to both the drugs. The patient was promptly started on treatment with anti-tuberculous medication. The patient was lost to follow up. Discussion Cutaneous TB forms a small proportion of extrapulmonary TB. Malnutrition and low socioeconomic conditions are predisposing factors for cutaneous TB. The incidence of cutaneous TB has fallen from 2% to 0.15% in India, whereas it is rare in developed countries. [3] This decline in incidence may be attributed to the availability of effective antitubercular drugs, elimination of milk-herds, and general improvement in the living standards. [3] But recently, there has been resurgence of cutaneous TB due to multidrug-resistant strains of M. tuberculosis and HIV pandemic. Skin TB has been classified into three main entities depending on the route of transmission and the state of host immunity. The first is primary cutaneous skin TB caused by M. tuberculosis complex (M. tuberculosis or M. bovis). The second and third entities are the secondary forms of skin TB resulting from direct spread to the skin from an underlying contiguous structure. [1] Primary inoculation TB results from direct inoculation of mycobacterium in the skin of a person who has no natural or artificial acquired immunity to the organism. The pathogenesis requires a breach in the continuity of skin from an abrasion or injury that allows the entry of tubercle bacilli. Causative organism of cutaneous TB are mainly M. tuberculosis, M. bovis, M. africanum, M. microti and atypical mycobacteria. However, M. tuberculosis is the most common organism. [1],[2],[4] Differential diagnoses include infection with atypical mycobacteria (called mycobacteria other than M. tuberculosis or MOTT), sarcoidosis, foreign body granuloma, syphilis, or sporotrichosis. [5] In general, MOTT are thought to cause mycobacterial skin disease more often than M. tuberculosis. Due to the fact that MOTT infections often closely mimic infections with M. tuberculosis, atypical mycobacteria was the differential diagnosis considered by clinicians in our case. But we isolated M. tuberculosis from the lesion which ensured proper diagnosis and correct treatment to the patient. Primary inoculation TB has been reported after blunt trauma, [1] as occupational disease subsequent to an autopsy of tuberculotic cadaver, [2] vaccination with bacillus Calmette-Guιrin (BCG), [6] intralesional steroid injection, [7] needle stick injury, [8] and blepharoplasty. [9] Recent case reports have described it as a complication of acupuncture [5],[10] and from the penetrating injury by knife. [4] This case is unique as infection by M. tuberculosis after vehicular accidental injury is not reported yet. As there was no primary focus identified in the skin or underlying bone, we presume the source of infection to be from environment which was inoculated into the skin at the time of injury or during the process of healing. Through this case report, we wish to stress that though the incidence of cutaneous TB is reported as less than 1% of all cases of TB, it is important for practitioners to consider this infection when faced with a suggestive clinical picture. It is imperative that physicians have a high index of suspicion in order to quickly and effectively diagnose and treat these substantially morbid skin conditions. This case report also demonstrates the importance of a proper history and physical examination as well as diligent laboratory and diagnostic testing in determining the aetiology of a suspicious and treatment-resistant skin lesion and appropriate management resulting in high patient satisfaction. Acknowledgment We acknowledge Professor and Head, Department of Skin and Venereal Diseases, T N Medical College for her support. References
Copyright 2012 - Indian Journal of Medical Microbiology The following images related to this document are available:Photo images[mb12020f2.jpg] [mb12020f1.jpg] |
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