The use of two substrates for indirect immunofluorescence in the diagnosis of pemphigus

Sir, Sea-urchins are found along the coastline, including in many tourism sites. Their spines consist of calcium carbonate crystals covered by a layer of epithelium. Injuries from seaurchins result from penetration of the spines into the dermis or subcutis, leading to pain of several days' duration. Complications include local inflammation and infection or a delayed granulomatous foreign-body reaction that can develop weeks or months later. The latter may often be followed by long-lasting pain and even by loss of function. To prevent these sequelae, most authors favour the excision of spines rather than waiting for spontaneous recovery as recommended by others. At present, no uniformly accepted successful treatment method is available. We found the erbium:YAG laser to be a suitable tool for effective removal of the spines. Four patients presented to our outpatient department about 1 week after a sea-urchin spinous injury during a vacation. They all suffered from severe pain and loss of function of the injured extremities. Previous attempts to remove the spines mechanically had not been successful. Inspection disclosed multiple black spines (. 50) up to 1 mm in diameter in the soles of the feet (Fig. 1A) in three of the patients. Mobility at the distal interphalangeal joints was reduced due to an accompanying erythematous oedema. The fourth patient had spines in the left index finger, with swelling and reduced flexibility. We decided to use the erbium:YAG laser (Medilas E, Dornier, Munich, Germany; spot size 2 ́5 mm, 300 mJ, fluence 6 J cm, repetition rate 5±10 Hz) to remove the foreign material. Three of the patients were treated under local infiltration anaesthesia (1% lidocaine without epinephrine), and one under general anaesthesia. The foreign bodies were destroyed leaving circumscribed crater lesions with tiny pinpoint areas of bleeding (Fig. 1B). Postoperatively, an antiseptic wound dressing was applied. In two of the patients we took a 2-mm skin biopsy; histological examination revealed penetration of the spines into the deep dermis and even subcutis. Two treatment sessions were necessary to remove all the widespread spines in two patients. The wounds re-epithelialized at the latest within 2 weeks after treatment; in some locations we saw focal hyperkeratosis but there were no signs of scarring. Figure 1(C) shows the typical appearance 4 weeks after treatment. Mobility and function of the distal phalanges were restored completely. During 1 year of follow-up no delayed granulomatous foreign-body reactions or other complications have been observed. Sea-urchins are relatively sedentary creatures often attached to rocks or corals. The porous spines penetrate the skin when stepped on. Mechanical extraction is almost ineffective because the spines fragment easily; surgical excision has been recommended, even though this is difficult with widespread injuries. Leaving spines in place leads to acute pain, local inflammation or infections and a risk of delayed granulomatous foreign-body reactions. There are reports of granulomatous inflammation in the dermis and subcutaneous tissues, with severe involvement of bone and cartilaginous surfaces followed by chronic pain and even loss of function.