Filarial elephantiasis of the scrotum presents as diffuse scrotal enlargement from hypertrophy and hyperplasia of the subcutaneous tissues and epidermis, which become leathery, coarse, and dry. Sebaceous glands are usually destroyed. The consistency of the leathery skin is that of nonpitting edema. The scrotum varies in size from slight enlargement to becoming monstrous in size, with the scrotum touching the ground and weighing as much as 200 pounds. The condition is indigenous to tropical areas. Filarial elephantiasis is caused by a nematode, Wuchereria bancrofti (90%), and is transmit- ted to man by certain mosquito species (Culex, Aedes, and Anopheles). Other thread-like parasitic worms such as Brugia malayi (10%) and Brugia timori (1%) may also cause elephantiasis. The adult worms in man are found in lymphatic channels and in subcutaneous tissues; the larval forms usually enter the bloodstream between the hours of midnight and 2 am. These microﬁlariae produce no general symptoms except those associated with obstruction of lymphatics. Scrotal elephantiasis is a late sequela of ﬁlarial infection and results from lymphatic obstruction. Secondary bacterial infections can accentuate the process. Usually, a history of repeated episodes of lymphangitis and lymphadenitis associated with fever, malaise, rash, and tender lymph nodes after inoculation is obtained. With each episode of diffuse enlargement and swelling, the regression and healing is less complete. Superﬁcial lymphatics may become dilated, rupture, and exude lymph.
Filariasis may begin as an insidious condition known as “lymph scrotum,” which is characterized by a mild enlargement of the scrotum along with cutaneous lymphatic ectasia. Three other presentations have been described with ﬁlariasis. The ﬁrst is somewhat similar to lymph scrotum but involves the spermatic cord, which feels like soft, compressible vessels. In another presentation, the spermatic cord contains thick, rubbery masses, which represent a late ﬁbrous reaction following lymphangitis. In this presentation, ﬁbrous nodules, distinct from the vas deferens, are palpated throughout the spermatic cord. The third type of presentation, called “mumu,” was observed during World War II as acute swelling and edema of the spermatic cord that gradually subsides after individuals leave an endemic area. This may represent an allergic reaction that develops following ﬁlarial inoculation.
Although positive skin tests and DNA polymerase chain reactions (PCRs) can detect ﬁlarial DNA and indicate disease, the deﬁnitive diagnosis is made by ﬁnding the microﬁlariae in the peripheral blood at night after ﬁltration through micropore membrane ﬁlters. This can also quantify the load of microﬁlariae. However, once lymphedema develops, the microﬁlariae are absent in peripheral blood. Speciﬁc drug therapy involves diethylcarbamazine (microﬁlaria and adult worms), ivermectin (microﬁlaria), albendazole (adult ﬁlarial worms), and possibly even doxycycline. Once lymphedema develops, there is no cure but reducing inﬂammation, and surgical removal of the elephantiasic genital tissue may help in selected cases.
Alternatively, elephantiasis may occur in the absence of parasitic infection. This nonparasitic form of elephantiasis is known as nonﬁlarial elephantiasis or “podoconiosis,” and occurs in high frequency in northern Africa. Nonﬁlarial elephantiasis is thought to be caused by persistent contact with irritant soils, or from lymphedema, lymph obstruction, or lymphangitis from a wide variety of causes, including infection. This elephantiasis may occur as a result of local disorders such as scrotal ﬁstulae, or following inguinal lymphadenectomy, metastatic carcinoma, or inguinal lymphangitis from syphilis, lymphogranuloma venereum, tuberculosis, or granuloma inguinale. Treatment is aimed at eradication of infection and supportive care for the enlarged scrotum.