Skin injuries caused by spines of various species of cactus are common in the southwestern United States and Mexico and have been described worldwide.1 Effects of injury vary depending on localization, surface extension, and skin conditions (eg, preexisting erosions, ulcerations, sunburns).
A 22-year-old woman presented to the outpatient department with extremely painful, erythematous papules on the second, third, and fourth fingers of the left hand, as well as diffuse swelling of the entire metacarpophalangeal and interphalangeal joints (Figure 1). She reported accidentally falling on a cholla cactus (genus Cylindropuntia) 2 weeks earlier while walking on a cholla cactus trail during a vacation in California. She reported that the symptoms had worsened over the last week. Class 3 corticosteroid ointments did not provide benefit. The patient had no comorbidities and was allergic to penicillin.
Radiographs of the left hand excluded concomitant fracture. Digital dermoscopy showed multiple white homogeneous areas with a central pustule (Figure 2A). Frequency-domain optical coherence tomography (OCT) displayed round hyperrefractive structures in the dermis suggestive of granulomas, as well as a small needlelike hyperrefractive structure, a foreign body (Figure 2B).
The few visible spines were immediately removed with tweezers; the patient remained symptom free for approximately 2 weeks. Subsequently, extreme pain developed in the left hand; the clinical presentation and pain did not respond to empiric intravenous antibiotic therapy with weight-calculated clarithromycin (500 mg twice daily), systemic analgesia with nonsteroidal anti-inflammatory drugs, and local therapy with antiseptics and class 3 corticosteroid ointment. Four days later, all 27 papules were excised with 3- and 4-mm punch biopsies using digital nerve blocks. Histology showed classic foreign body granulomas with hematoxylin and eosin stain (Figure 2C).
One week later, pain, erythema, and swelling had disappeared; no additional lesions had developed (Figure 3). Follow-up OCT showed no foreign bodies. At 4-week follow-up, the inflammatory component had disappeared, and no granulomas were evident. Six months later, the lesions healed with minimal scarring that could later be treated with fractional laser therapy (Figure 4).
Pathogenesis and Presentation
Cactus spines are included in the possible causes of foreign body granulomas of the skin (eTable).2,3 However, granulomatous inflammation after cactus spine injury rarely has been described in the medical literature. In the first known case report in 1955, Winer and Zeilenga4 described a woman who developed multiple hand granulomas that were partially removed by curettage, while the spines underwent slow spontaneous expulsion.
In 1971, Schreiber et al5 hypothesized a type 2 allergic response to cactus spines based on the variability of reactions in different cases. Doctoroff et al6 proposed an unroofing technique based on the removal of spines under microscopy, which brought faster (2–4 months) healing. Madkan et al7 reported that complete response is possible only with punch excision of the largest lesions.
The cholla (Cylindropuntia) cactus has been described as the species most commonly implicated in granulomatous reactions to cactus spines.8,9 Two principal pathogenic mechanisms have been described—foreign body granuloma and allergic reaction to cactus antigens—because not every patient develops granulomatous lesions.
Complications of injury from cactus spines are common, especially when spines are not completely removed, including local inflammation, superinfection, necrosis, allergic reactions, granulomas, scarring, and chronic pain. Rare consequences of cactus injury include bacterial infection with Staphylococcus aureus; Enterobacter species; atypical mycobacteria, including Mycobacterium marinum; Nocardia species; and Clostridium tetani, as well as deep fungal infection, especially in immunocompromised patients.10 In our case, bacterial culture and polymerase chain reaction testing for mycobacteria were negative.
Cactus spine injuries usually are easy to diagnose based on the clear-cut anamnesis and clinical picture; however, it might be interesting to assess the presence of foreign body granulomas without biopsy. Optical coherence tomography is a noninvasive optical imaging technique based on low-coherence interferometry that uses a low-intensity, 1310-nm infrared laser. Widespread in ophthalmology, OCT has gained importance in dermatologic diagnostics, especially for nonmelanoma skin cancer.11 Moreover, it has demonstrated its usefulness in various dermatologic fields, including granulomatous lesions.12 Further methods include reflectance confocal microscopy, based on a near-infrared laser, and 7.5-MHz ultrasonography. In our experience, however, 7.5-MHz ultrasonography has been ineffective in detecting cactus spines in the current patient as well as others. Preoperative and postoperative monitoring with dermoscopy and OCT helped us evaluate the nature, size, and location of spines and lesions and effective healing.
Management strategies are still debated and include watchful waiting, corticosteroid ointment, partial removal of spines, and unroofing.1,2,4-10,13-18 We treated our patient with an innovative radical surgical approach using punch excision for granulomas that developed after cholla cactus spine injury. Our approach resulted in rapid relief of pain and reduced complications, a good aesthetic result, and no recurrence.