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Identification of Mycobacterium marinum in sea-urchin granulomas
C De la Torre1, A Vega, A Carracedo
1Service of Dermatology, Complejo Hospitalario de Pontevedra, C/Loureiro Crespo s/n, 36001 Pontevedra, Spain. ctorre@arrakis.es
Background:
Sea-urchin granuloma is a chronic granulomatous reaction arising after injury with sea-urchin spines. Classified as an allergic foreign-body type of granuloma, it is believed to be a delayed-type reaction to an as yet unidentified antigen. In a clinicopathological study, 50 biopsy specimens from 35 patients diagnosed as having sea-urchin granuloma caused by Paracentrotus lividus, we found different inflammatory patterns that in some cases suggested a mycobacterial infection.
Objectives:
To investigate and identify mycobacterial DNA in formalin-fixed and paraffin-embedded skin biopsy specimens diagnosed as sea-urchin granulomas.
Methods:
A search combining polymerase chain reaction amplification using Mycobacterium genus-specific primers, and subsequent restriction enzyme analysis enabling identification to the species level, was performed in 41 samples.
Results:
Amplification of a 924-bp DNA fragment encoding mycobacterial 16S rRNA gene was positive in eight biopsy specimens from seven patients (21%). M. marinum-specific restriction patterns were identified in three samples.
Conclusions:
Although further controlled studies are necessary, from these data it would appear that mycobacteria may play a pathogenic role in some cases of sea-urchin granuloma.