A Woman with Knee Pain and Soft-Tissue Calcification

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The patient reported a history of having had a thread-like worm at 10-12 years of age (i.e., >50 years before presentation). At that time, she was a resident of Najran, Saudi Arabia, and recalled experiencing intense itching in the lower limbs, followed by the emergence of a small worm that her family removed by wrapping it around a stick. Since then, she had experienced no associated problems. Radiographs of the patient's knees revealed guinea worm calcifications. Serpentine soft-tissue calcification is seen within the distal aspect of the right thigh and around the left knee (figure 1). The calcification appears nodular, beaded, and fragmented because of the breaking up of the worm (figure 2). The characteristic appearance, combined with the patient's background, led to a diagnosis of infection due to D. medinensis (guinea-worm), a nematode parasite that causes dracunculiasis. After the death of an adult worm, D. medinensis may undergo calcification in several forms, especially if it was not fertilized or did not release its larvae. In its typical location in the lower extremities, the female D. medinensis appears as a long, stringlike, serpiginous or curvilinear calcification, which may extend to 1 meter in length [1]. A description of D. medinensis infection was given by ArRazi Al Hawi several hundred years ago [2]. The disease is a debilitating and painful infection that begins with a blister, usually on the leg, followed by itching, fever, swelling, and burning sensations. Once the infected person immerses the infected part in open water, the worms emerge and release thousands of larvae into the water. The larva is then ingested by a water flea (cyclops), where it develops and becomes infective. Humans acquire infection by drinking water contaminated with cyclops. The D. medinensis larva then penetrates the gut wall and migrates through the subcutaneous tissue,