Tan S H, Tan B H, Goh C L, Tan K C, Tan M F, Ng W C, Tan W C
Institute of Dermatology, National Skin Centre, and Department of Medicine, National University Hospital, Singapore.
Int J Dermatol. 1999 Feb;38(2):122-7. doi: 10.1046/j.1365-4362.1999.00576.x.
The objective of this study was to explore the role of the polymerase chain reaction (PCR) fo the detection of Mycobacterium tuberculosis DNA as a diagnostic aid in cutaneous tuberculosis using routinely processed skin biopsy specimens.
A wide range of clinical specimens representing different forms of cutaneous tuberculosis and so-called tuberculids were studied. A sensitive and specific PCR assay targeting the sequence IS6110 of Mycobacterium tuberculosis complex was used. The specimens were categorized as follows. 1 Acid-fast bacilli (AFB) positive on biopsy (nine specimens from seven patients who were immunocompromised). PCR was positive in five specimens. Of these, one specimen was culture positive and three specimens were culture negative. 2 AFB negative on biopsy: (a) tuberculosis verrucosa cutis (23 specimens); (b) lupus vulgaris (three specimens); (c) cutaneous tuberculosis clinically suspected (six specimens). PCR was negative in all specimens. 3 Tuberculids.' (a) erythema induratum/nodular vasculitis (20 specimens); (b) papulonecrotic tuberculid (two specimens); (c) erythema nodosum (20 specimens). PCR was negative in all specimens.
The role of PCR in clinical dermatologic practice, at this stage, may be in differentiating between cutaneous tuberculosis and atypical mycobacterial infections in the context of an immunocompromised patient where AFB can be demonstrated on biopsy and cultures may be negative. In this clinical situation, PCR allows the prompt diagnosis and early institution of appropriate therapy. We have not found PCR to be a useful complement to the clinical and histologic diagnosis of "paucibacillary" forms of cutaneous tuberculosis.
本研究的目的是探讨聚合酶链反应（PCR）检测结核分枝杆菌DNA在利用常规处理的皮肤活检标本诊断皮肤结核中的辅助作用。
研究了一系列代表不同形式皮肤结核及所谓结核疹的临床标本。采用了针对结核分枝杆菌复合群IS6110序列的灵敏且特异的PCR检测方法。标本分类如下。1.活检中抗酸杆菌（AFB）阳性（来自7例免疫功能低下患者的9份标本）。PCR在5份标本中呈阳性。其中，1份标本培养阳性，3份标本培养阴性。2.活检中AFB阴性：（a）疣状皮肤结核（23份标本）；（b）寻常狼疮（3份标本）；（c）临床疑似皮肤结核（6份标本）。所有标本PCR均为阴性。3.结核疹：（a）硬结性红斑/结节性血管炎（20份标本）；（b）丘疹坏死性结核疹（2份标本）；（c）结节性红斑（20份标本）。所有标本PCR均为阴性。
现阶段，PCR在临床皮肤科实践中的作用可能在于，在免疫功能低下患者的活检中可发现AFB而培养可能为阴性的情况下，区分皮肤结核与非典型分枝杆菌感染。在这种临床情况下，PCR可实现快速诊断并尽早开始适当治疗。我们尚未发现PCR对“少菌型”皮肤结核的临床和组织学诊断有辅助作用。
