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Findings: An AP view of the knees (Image #1) demonstrates multiple curvilinear calcifications within the soft tissues of the thighs and right calf. The soft tissue calcifications appear more linear adjacent to the proximal tibia in the right calf. Similar curvilinear calcifications are noted within the soft tissues surrounding the right and left hips (images # 2 and #3), left wrist (image #4), proximal left humerus (image #5), and the right chest wall (image #6). Incidental note is made of degenerative changes in both knees.

Diagnosis (Provisional): Dracunculiasis (Guinea Worm Disease).

Discussion: A wide variety of entities are associated with soft tissue calcification. Resnick classifies conditions that lead to calcification in the soft tissue into three types: (1) Metastatic calcification related to a disturbance in calcium or phosphorus metabolism. This would include etiologies such as hyperparathyroidism, renal osteodystrophy, hypoparathyroidism, hypervitaminosis D, milk alkali syndrome, sarcoid, and certain metastatic lesions. (2) Calcinosis in the skin and subcutaneous tissues in the presence of normal calcium metabolism. Tumoral calcinosis as well as collagen vascular diseases such as scleroderma and dermatomyositis fall into this category. (3) Dystrophic calcification related to calcium deposition in damaged or devitalized tissues in the absence of a generalized metabolic disorder. The entities in this group are many including neoplastic, inflammatory, and traumatic conditions.

In this case, as in most cases, the appearance of the soft tissue calcification is key in steering one in the right direction toward the diagnosis. For example, processes that tend to be periarticular in location include hyperparathyroidism, renal osteodystrophy, milk alkali syndrome, hypervitaminosis D, and collagen vascular diseases. If one were to see a reticulated pattern of calcification, dermatomyositis might come to mind. Conversely, bulky calcification may raise the question of tumoral calcinosis amongst other things. The calcifications in this case are curvilinear in shape, at multiple sites, and are not exclusively periarticular. The appearance of these calcifications would be atypical for most metabolic, neoplastic, or collagen vascular entities. Given the patient's clinical history, an infectious etiology (specifically parasites) should bed entertained. Indeed, this picture is felt to be most compatible with dracunculiasis.

Dracunculiasis is caused by the human ingestion of the guinea worm Dracunculus medinensis. The disease is seen in parts of Africa, India, Pakistan, the Middle East, and South America. Humans contract the helminths when larvae in contaminated water are ingested by a water flea (Cyclops) and then, in turn, are swallowed in drinking water by people. The larvae enter the circulation and mature in the subcutaneous tissues. When the female worm dies, it may calcify producing long curvilinear radiointense shadows. For some reason, the male worm tends not to calcify. The curled soft tissue calcifications are often seen in the lower extremities and hands. Less common involvement is seen in the perineum and chest and abdominal wall. If the worms die adjacent to an articular surface, a severe cellular reaction with an associated joint effusion and even bony destruction can occur. One study notes an increased incidence in the risk of malignancy in patients with calcification due to the guinea worm. Specifically, bladder carcinoma was the most common.

References:
Resnick D, Niwayama G. Diagnosis of Bone and Joint Disorders,
W. B. Saunders Company, 1988.

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