Case Study: Acute Dermatitis and Pain Following Marine Exposure in the Adriatic Sea

Case at a Glance

A 33-year-old female tourist in Croatia developed an acute, intensely painful, erythematous, and blistering skin lesion on her thigh after sitting on a submerged rock in shallow seawater. The clinical presentation and geographical location were highly suggestive of envenomation by a marine organism, most likely a sea urchin.

Patient's Story

The patient, a 33-year-old female on holiday in Croatia, presented with a chief complaint of a severe skin reaction. She reported that while sitting on a rock in shallow, calm seawater, she experienced a sudden, intense burning and stinging sensation on her posterior thigh. Over the subsequent few hours, the affected area became progressively more erythematous, darkened in color, and developed small vesicles (blisters). With plans to fly back to the United Kingdom the following day, she sought advice regarding the potential cause and appropriate management.

Initial Assessment

On presentation (inferred from patient's description and photograph), there was a localized, well-demarcated area of inflammation on the patient's thigh. The lesion was characterized by significant erythema (redness), some violaceous discoloration, and early vesiculation. The patient reported the pain as severe and constant, with a burning quality. There were no immediate signs of systemic reaction, such as respiratory distress, angioedema, or hemodynamic instability.

The Diagnostic Journey

The primary diagnostic consideration was an injury from a marine organism. The patient's history of sitting on a rock immediately preceding the onset of symptoms made direct contact with a benthic (sea-floor dwelling) creature highly likely. The Adriatic Sea is known for its populations of sea urchins (Echinoidea), which are commonly found on rocks in shallow coastal waters. The clinical picture of intense, immediate pain followed by progressive inflammation and blistering is classic for sea urchin envenomation. The tiny, brittle spines can break off in the skin, delivering venom and acting as a foreign body, triggering a robust inflammatory response. Other differentials, such as a jellyfish sting, were considered less likely given the specific mechanism of injury (contact with a stationary object on the seafloor).

Final Diagnosis

Probable Marine Envenomation secondary to Sea Urchin (Echinoidea) sting.

Treatment Plan

Given the patient was traveling, immediate and follow-up advice was crucial.

1. Immediate First Aid: The patient was advised to immerse the affected area in hot water (43-45°C or 110-113°F), as hot as can be tolerated without scalding, for 30-90 minutes. This heat helps to denature the heat-labile proteins in the venom, providing pain relief.
2. Spine Removal: Careful inspection of the wound for any visible spines and removal with fine-tipped tweezers. The patient was cautioned against probing deeply or aggressively, which could fracture the spines and complicate removal.
3. Wound Care: Gentle cleansing of the area with soap and water, followed by application of a topical antiseptic or antibiotic ointment to prevent secondary infection.
4. Symptom Management: Over-the-counter analgesics (e.g., ibuprofen) were recommended for pain and inflammation. An oral antihistamine could be used to manage pruritus (itching) if it developed.
5. Medical Follow-up: The patient was strongly advised to seek a formal medical evaluation upon her return to the UK to ensure no spines were retained and to assess for signs of infection. Retained spines can lead to chronic inflammation, foreign body granuloma formation, and persistent pain.

Outcome and Follow-up

The patient's immediate outcome following travel is unknown. However, with appropriate care, the prognosis for such injuries is generally excellent. Follow-up is essential to address the potential complications of retained spines and secondary bacterial infections. In some cases, a course of antibiotics is prescribed prophylactically or to treat an established infection. Complete resolution of the lesion can take several weeks, sometimes with residual post-inflammatory hyperpigmentation.