Plant or cactus thorns can result in a synovitis due to direct migration of the thorn.
Features of plant or cactus thorn synovitis:
(1) The patient develops an inflammatory arthritis, usually a monoarthritis.
(2) It affects a joint exposed to a thorn, so usually on an extremity.
(3) Granulomatous synovitis is seen on histologic exam.
(4) Fragments of thorn material may be identified on the histologic exam. This may be enhanced by use of polarized light.
Reasons for a delay in diagnosis:
(1) The patient fails to recall the presence of a thorn.
(2) The inflamed synovium is not biopsied.
(3) Fragments of thorn material are not identified in the histologic section.
(4) The synovitis is ascribed to a different cause.
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Specialty: Emergency Medicine, Critical Care
