Gruźlica toczniowa małżowiny usznej

Introduction

Cutaneous tuberculosis is a rare extrapulmonary manifestation of tuberculosis with a prevalence estimated at approximately 1.5%, though recently there has been an increase in the incidence of the disease which can be explained by its link with immunosuppression, such as AIDS or chemotherapy, and the selection of drug-resistant strains [1–3]. In Europe and in the USA, the highest prevalence is noted among adults [4], with women affected more often than men [1]. Lupus vulgaris is considered to be the most common form of cutaneous tuberculosis, although many authors claim that tuberculosis colliquativa cutis (scrofuloderma) seems to be more widespread, especially in children [1, 4]. The final diagnosis of cutaneous tuberculosis is based on the joint consideration of clinical, histological and bacteriological criteria [1]. The treatment is based on a combination of antimycobacterial drugs [4].

Case report

A 70-year-old woman with a history of hypertension, type 2 diabetes and atrophic macular degeneration (AMD) was admitted to the Department of Dermatology for the diagnosis and treatment of skin lesions involving the left auricle, recurrent for many years and, at the time of admission, exacerbated for the past 3 months, with no improvement after outpatient treatment. In the past, the patient reported frostbite of the left ear and periodically occurring oedematous erythematous lesions with vesicles located within the left auricle, accompanied by a burning sensation and recurring in autumn and winter, linked by the patient to her use of a wool duvet. On admission, a dark red oedematous erythematous lesion with mild skin exfoliation was noted in the lower two-thirds of the left auricle and partially within the angle of the mandible and the external acoustic opening, and accompanied by bilateral tinnitus (fig. 1). Direct mycological examination of material collected from the lesion revealed a few clusters of yeast-like fungi. The smear test was negative for pathogenic bacteria. Diascopy showed the “apple jelly” sign (fig. 2). Skin patch tests as well as serological tests for Lyme disease were negative. The results of other laboratory tests were within the normal range. The only finding in chest X-ray was increased stromal pattern, and computed tomography scan of the chest revealed two calcified nodules, 4 mm in diameter, in segment 3 of the right lung. A skin specimen was obtained from the lesion for histopathological examination, showing inflammatory and granulomatous changes suggestive of sarcoidosis, without a possibility to perform staining for mycobacteria. Two months later, the patient was re-admitted to the Department. The clinical presentation of the dermatosis was the same as previously (fig. 3). Repeated histopathological examination of a skin specimen from the lesion also revealed granulomatous changes of the “naked” granuloma type potentially consistent with sarcoidosis, demonstrating features which, despite negative results of mycobacterial staining, did not rule out tuberculosis.
The patient was re-admitted to the Department for the third time a month later in order to expand the diagnostic work-up. Further material was obtained from the patient for testing. Direct bacterioscopy did not detect the presence of mycobacteria, and genetic probe test and Quantiferon test were negative. A month later a culture test was found to be positive, and the detected strain was classified as Mycobacterium tuberculosis complex. After pulmonology consultation a decision was made to start antimycobacterial treatment with rifampicin, ethambutol, isoniazid and pyrazinamide. On account of AMD, previously complicated by retinal detachment and potentially coexisting with optic nerve damage, a consultant ophthalmologist suggested that ethambutol should be discontinued. In the first week of therapy with rifampicin, isoniazid and pyrazinamide, the woman was hospitalised in the Department of Dermatology.
During the treatment, the patient developed multiple adverse effects including hyperuricaemia, elevated transaminase activity, and generalised skin rash. Additionally, the results of drug-resistance testing of mycobacteria were obtained, showing resistance to rifampicin. After repeated pulmonary consultation it was decided to transfer the patient to the Department of Pulmonary Diseases to continue treatment with intramuscular streptomycin (fig. 4). After 10 months of antimycobacterial therapy according to the regimen containing streptomycin, isoniazid and pyrazinamide for 2 months followed by pyrazynamide and isoniazide for 8 months, complete resolution of skin lesions was achieved.

Discussion

Primary involvement of the ear in lupus vulgaris is extremely rare, but in our patient it was the first and only location of skin lesions [3]. The differential diagnostic process may include a variety of disorders, including granulomatous diseases, but in patients with lesions located within the ear, tuberculosis is most commonly mistaken for chilblain lupus erythematosus, a form of sarcoidosis [1]. “Turkey ear” is a clinical term used in the past to describe oedematous erythematous lesions within the ear lobe which are observed in chilblain lupus erythematosus. However, some reported cases indicate that such lesions can also occur in lupus vulgaris, so the presentation is not pathognomonic and thus requires a broader diagnostic approach [1, 5]. In cases involving deep lesions, yellowish-brown foci resembling apple jelly can be observed by diascopy, as in the case of the reported patient [1]. Lupus vulgaris usually develops as a reactivation of infection in individuals with a previous history of lung involvement. Therefore, the case reported above seems atypical because of the lack of conclusive evidence of primary lesions in the respiratory tract or any other sites. The only suspicious findings could be the lung nodules found on computed tomography scans [4]. It is a type of tuberculosis associated with a low mycobacterial load, so culture tests are usually difficult and produce negative results. Consequently, the polymerase chain reaction method could be more beneficial in such cases. Despite the availability of advanced molecular biology techniques, it is worth noting that in our patient no mycobacterial genetic material was identified in the collected skin specimen, whereas the traditional culture test was positive [3, 5]. Diagnostic difficulties associated with cutaneous tuberculosis are mainly due to the low mycobacterial load present in skin lesions caused by the phagocytosis of mycobacteria by connective tissue cells, reduced mycobacterial penetration through connective tissue fibres, and attenuation of mycobacterial virulence by mucopolysaccharides. The diagnosis of cutaneous tuberculosis requires obtaining a skin sample and examining it by microbiological and histological methods [4, 6].
In addition to diagnostic difficulties, the case reported above also involved therapeutic dilemmas. Already at the beginning of treatment, the patient was found to be refractory to therapy with rifampicin, the main bactericidal (antimycobacterial) drug. Isolated mycobacterial resistance to rifampicin (RMP-resistance) is considered to be very rare and, furthermore, associated with a worse prognosis. Most likely, it results from spontaneous mycobacterial chromosomal mutations within the rpoB gene which is part of RNA polymerase [7]. Additional therapeutic difficulties included ophthalmic contraindication to treatment with ethambutol, and the development of adverse drug reactions.

Conclusions

In view of the increasing prevalence of tuberculosis the condition must be taken into consideration in the differential diagnostic work-up, as delayed diagnosis and hence late introduction of treatment may lead to an increase in patient mortality.

Conflict of interest

The authors declare no conflict of interest.

References/Piśmiennictwo

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