Dermatology Online Journal

Sea urchin granuloma secondary to Strongylocentrotus purpuratus and Strongylocentrotus franciscanus
Filamer D Kabigting, Stephan J Kempiak MD PhD, Doru T Alexandrescu MD, Benajmin D Yu MD PhD
Dermatology Online Journal 15 (5): 9

Department of Dermatology, University of California at San Diego, San Diego, California. byu@ucsd.edu

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Abstract

Sea urchin injuries have been associated with a variety of cutaneous lesions, ranging from acute, transient reactions, to more chronic inflammatory conditions that result in the formation of granulomas. Although diverse species of sea urchins have been reported to produce chronic cutaneous granulomas, the two most prevalent organisms found on the US West Coast, purple and red sea urchins (Strongylocentrotus purpuratus and Strongylocentrotus franciscanus), have not yet been reported to induce persistent granulomatosis in humans. We describe one case of a 35-year-old marine biologist with chronic cutaneous lesions produced after repeated exposures. The lesions were similar to the ones produced by other urchin species, consisting of small, firm, erythematous nodules on his palms, dorsum of the hands, elbows, and knees. Increased awareness of this condition, including its association with the two prevalent organisms on the West Coast, should lead to a more rapid diagnosis for those affected. This article reviews the types of injuries, clinical cutaneoous lesions, histopathological features, and pathogenesis of the chronic inflammatory process induced by sea urchins.

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Introduction

Injuries from marine organisms may cause considerable morbidity in humans. Sea urchin-related injuries are especially common given the ubiquity of these marine bottom dwellers and the high levels of human contact related to recreational and commercial activities. Acute penetrating injuries from sea urchin spines are common and can resolve spontaneously within days. However, chronic lesions may develop persistent inflammation due to retained spine fragments in the skin and resultant granuloma formation [1]. We present a case of sea urchin granulomas related to repeated exposures from his doctoral research activities. The purple and red sea urchins (Strongylocentrotus purpuratus and Strongylocentrotus franciscanus, respectively) involved in this case are the most prevalent sea urchins encountered on the West Coast. These two species have not previously been reported to produce sea urchin granulomas. The patient was treated with topical corticosteroids with moderate improvement. This article reviews the types of injuries, clinical cutaneoous lesions, histopathological features, and the pathogenesis of the chronic inflammatory process induced by the sea urchins.

Case report

A 35-year-old man without any notable medical co-morbidities presented with a 3-month history of multiple papules and nodules on his hands, elbows, and knees. These lesions were slightly pruritic, but otherwise non-tender and non-draining. He denied similar appearing lesions in the past and was otherwise in good health and without any associated symptoms. There was no history of recent travel or contacts with any individuals with skin eruptions. He was taking no medications. The patient is a marine biologist who frequently handles sea urchins and other crustaceans related to his research along the coast of southern California.

Figure 1a	Figure 1b
Figure 1. Erythematous, nontender nodules are present on the right knee (1A) and palm (1B)

On physical exam, there were small, firm, erythematous papules and nodules on his palms, dorsa of the hands, elbows, and knees (Fig. 1A). Of note, one lesion on the right hand had a central punctum filled with black material (Fig. 1B). No other skin lesions were noted. There was no associated lymphadenopathy.

Figure 2
Figure 2. Dense dermal granulomatous infiltrate with lymphocytes and histiocytes. (H&E, x40)

A 4 mm punch biopsy for microscopic examination and tissue culture was obtained from a representative nodule located on his right knee (Fig. 2). Hematoxylin-eosin-stained sections revealed features consistent with a foreign body granulomatous pattern, including a diffuse dermal infiltrate with a predominance of epitheloid cells and lymphocytes. The granulomas contained Langerhans-type giant cells and some exhibited centers with necrotic material. Gram, Fite-Faraco, acid-fast stains, and cultures for bacteria, mycobacteria, and fungi were negative.

Based on the history of repeated handling of sea urchins with occasional penetrating injuries from sea urchin spines and the histopathological findings, the patient was diagnosed as having sea urchin dermatitis. Several treatment options were presented to the patient including topical steroids, intralesional steroids, and surgical excision. Initially, the patient was treated with fluocinide 0.05 percent ointment applied twice daily. After 6 weeks, moderate improvement was noted in the degree of erythema and the size of the nodules; significant flattening of the papules and nodules was appreciated.

Discussion

More than 700 known species of sea urchins have been identified, among which 80 are known to be toxic to humans. Sea urchins are docile animals whose sharp, fragile spines can penetrate into human skin (commonly divers or fisherman) then easily break apart, leaving the unlucky host with pain, erythema, and tattoo-like stains from the foreign material. Acute symptoms usually resolve in a few days or weeks, even without treatment, unless injuries are complicated by secondary infection or chronic inflammation related to retained spine fragments.

Sea urchins are also associated with the production of various toxic substances, including corticosteroids, serotonin, glycosides, cholinergic agents and bradykinin-like substances contained within the hollow spines or specialized pincers, which are found at the base of spines called pedicellaria [2, 3]. Exposure to these toxins may produce pain out of proportion to injury. In rare cases involving a bolus of toxin, systemic symptoms including paresthesias, hypotension, and weakness may result. The flower sea urchin, Toxopneustes pileolus, reputably the most toxic of all sea urchins, contains potent neurotoxins which can cause pain, numbness, muscle paralysis, respiratory distress, and even death [4].

Dramatic sequelae can result from either penetrating spine injuries or from retained spine fragments that initiate a foreign body inflammatory response. Granulomas are typically the resulting chronic lesions. They may appear after a latency period of up to six months after the initial injury [5]. The first case of cutaneous granulomas secondary to sea urchin spine injury was reported by Gaté in 1936 [6]. Sea urchin granulomas typically measure 2-5 mm and appear as flesh-colored to slightly purple, firm, papules and nodules located on the hands and feet. These can develop shortly after primary injuries or may appear after a latency period ranging from a few weeks to months. In most instances only a few granulomas are seen, although there are case reports of as many as 200 lesions in a single patient [7].

Other manifestations of chronic sea urchin spine injury include arthropathy, neuropathy, or local bone destruction, depending upon where the injury occurs. Tenosynovitis may also occur if spine punctures involve the joint spaces or tendons of the hands or feet; chronic lesions can potentially lead to joint space destruction and functional impairment [8, 9].

Histopathological examination of sea urchin granulomas reveals a predominant granulomatous inflammatory reaction, of which foreign body and sarcoidal reaction patterns are most common [8]. However, necrobiotic, suppurative, tuberculoid, and nonspecific patterns of inflammation have also been reported [10]. Occasionally, Langerhans-type giant cells or vacuoles containing foreign-body material, presumably retained spinous fragments, may be observed. However, in a majority of cases, no foreign body material or microorganisms are detected. In a series of 35 patients with 50 biopsy specimens clinically-diagnosed as sea-urchin granulomas, de la Torre et al. [10] identified foreign material in only 16 percent of biopsies. Additionally, no polarized material was identified in any slides examined. The yet-to-be-identified antigens or tiny fragments responsible for stimulating the inflammatory response may exist at undetectable levels, or perhaps have already been eliminated by the time of the histological examination.

The pathogenesis of sea urchin granulomas remains unclear. They likely form as a multiphase mixed immunologic and foreign body response; responsible stimuli are both organic and foreign body in nature. The most common foreign body materials related to sea urchins include inorganic constituents of sea urchin spines such as various carbonates and sulfates. Organic antigens may be microbial, proteins-derived from spine epithelium, or foreign organic material introduced into the skin with the penetrating injuries. Evidence for Mycobacterium marinum positivity by polymerase chain reaction (PCR) was found in 20 percent of biopsy samples, as reported by De la Torre et al. [11]. All Ziehl-Neelsen stains and cultures were negative for mycobacteria in this series.

Toxins and other bioactive substances produced by sea urchins and contained within pedicellariae or spines may also play a pathogenic role in granuloma formation. Sea urchin lectin (SUL-1) produced by Toxopneustes pileolus has been shown to induce dendritic cell maturation in vitro [12]. SUL-1 matured dendritic cells are capable of promoting Th1 polarization, enhanced cytotoxic T-lymphocyte (CTL) responses, and increased IFN-γ secretion, all of which are pathogenically associated with a granulomatous response. Other yet unknown bioactive substances associated with sea urchins may produce similar immunologic activation.

Acute sea urchin injury sites should be immersed in hot water to inactivate toxins and to relieve pain. Additionally, spines need to be removed by gentle traction to prevent further toxin release. Antibiotics are considered only for suspected superinfection with bacteria or atypical mycobacterium, such as M. marinum. Sea-urchin granulomas may be treated initially with topical or intralesional steroids; varying degrees of efficacy have been reported in the literature.

Although some nodules can resolve spontaneously after a few years, others require surgical excision, particularly if they involve joints or produce functional impairment. X-rays may be considered to confirm the presence of retained spines that may require surgical removal. Erbium-YAG laser ablation is another reportedly effective, non-surgical treatment modality used to destroy retained sea urchin spines [13].

Figure 3
Figure 3. Purple and red sea urchins (Strongylocentrotus purpuratus and Strongylocentrotus franciscanus, respectively). (Image captured by patient.)

In conclusion, sea urchins produce skin reactions that may be either acute or delayed, which have a presumed immunologic basis. Such cutaneous lesions may represent a reaction to amorphous substances, mycobacteria or bacterial organisms, toxins produced by the echinoderms, or other toxins. We report an association of the chronic cutaneous granulomatous reaction with Strongylocentrotus purpuratus and Strongylocentrotus franciscanus, the two predominant species of sea urchins found throughout the North American Pacific seaboard (Fig. 3). Increased awareness of this condition, including its association with the two prevalent organisms on the West Coast, should result in improved diagnosis and treatment in these patients.

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