Detection of Mycobacterium tuberculosis DNA in lobular granulomatous panniculitis (erythema induratum-nodular vasculitis).

Objective: To determine, using polymerase chain reaction (PCR) amplification, if Mycobacterium tuberculosis complex DNA is present in the skin biopsy specimens of lobular granulomatous panniculitis.
Design: A retrospective descriptive study.
Setting: A university-based hospital.
Patients: From the 65 patients included in the study, we examined 72 paraffin-embedded skin biopsy specimens with a histologic diagnosis of erythema induratum or nodular vasculitis. The biopsy specimens were from the histopathological archives of the Departments of Dermatology and Pathology of the Hospital de la Santa Creu i Sant Pau, Barcelona, Spain, from 1976 to 1994. Twenty-two biopsy specimens were excluded from the final analysis because we could not amplify the internal control.
Main Outcome Measures: Detection of a 123-base pair fragment of the IS6110 insertion sequence specific for M tuberculosis complex.
Results: The results of PCR amplification were positive for M tuberculosis complex DNA in 77% of the skin biopsy specimens. No significant difference could be detected with respect to the age of the patients, ulceration of the nodules, reactivity to purified protein derivative, abnormal results of a chest x-ray examination, personal and family history of tuberculosis, and PCR results. The presence and degree of necrosis on histologic examination were significantly higher in the PCR-positive group (P = .04). None of the following variables were associated with PCR results: presence of vasculitis, degree of granulomatous infiltrates, number of giant cells, and presence of well-organized granulomas.
Conclusions: The DNA of M tuberculosis can be detected in a considerable number of skin biopsy specimens of lobular granulomatous panniculitis. None of the clinical and histologic variables evaluated could accurately predict the results of PCR amplification.