Cystic lymphangioma of the scrotum

Findings

Gray-scale ultrasound (US) imaging performed with a 12-MHz linear array transducer (HDI 3000, Advanced Technologies Limited, Bothell, WA) revealed a cystic mass with multiple septae in the scrotum (Figure 1). Few of the locules had fine moving internal echoes (Figure 2).

Color Doppler imaging showed blood flow within the septae (Figure 3). The spectral waveform showed a high-resistance arterial pattern. The testes and cord were seen to be separate from the mass and were normal.

A preoperative diagnosis of cystic lymphangioma of the scrotum was made based on characteristic US features. The US of the pelvis was normal. Computed tomography (CT) of the pelvis and upper thighs ruled out any extrascrotal extension of the lesion. At surgery, a large multi-loculated cystic mass was found within the scrotum, which was densely adherent to the tunics. The testes were seen separately, and a plane of dissection could be found between the testes and the mass. Complete excision of the mass was performed.

CLINICAL FINDINGS

Macroscopic examination showed a soft, fluctuant, well-circumscribed mass with irregular cystic spaces filled with whitish fluid and some cysts containing dark-colored fluid, which was supposed to be blood. Histopathologic examination revealed multiple dilated spaces lined by a single layer of epithelium and lymphocytes (Figure 4). Lymphoid follicles were found in the intervening stroma. Also, vessels with hypertrophied muscular walls (Figure 4) were seen that correlated well with the vessels showing flow in the septa of the cysts seen on color Doppler (Figure 3).

Discussion

Cystic lymphangiomas are congenital lymphatic hamartomas, half of which are recognized at birth, 90% of which are evident by the age of 2 years, and 95% of which occur in the neck or axilla.¹ The scrotum is an uncommon site for lymphangioma, and when the lesion is located on the scrotum, it is commonly misdiagnosed as a hernia, hydrocele, varicocele, or acute scrotal conditions, which may result in inappropriate therapy with a risk of reoccurrence.^1,2 Lymphangiomas result from the lack of adequate drainage from sequestered lymphatic vessels and are considered to be lymphatic hamartomas.³ Most of these are congenital, due to insufficiency or atresia of the efferent lymphatics or lack of communication between lymphatics and venous channels.³These lesions can also be acquired because of obstruction of lymphatics after inflammation, trauma, or degeneration.⁴ There are primarily 3 types of lymphangiomas based on histology: Capillary, cavernous, and cystic. The cystic form is the most common variety.

Histologically, lymphangiomas are composed of an increased number of dilated lymphatic channels that are lined by endothelium. The cystic spaces are filled with proteinaceous lymph fluid (without erythrocytes). Surgical trauma or damage caused by tissue handling during processing can result in hemorrhage, which can make the diagnosis of lymphangioma difficult to differentiate from hemangioma or Kaposi's sarcoma. The connective tissue stroma consists of varying amounts of spindle-shaped smooth muscle cells, collagen bundles, fibroblasts, and lymphocytes. The presence of benign lymphoid aggregates is helpful in the identification of lymphangiomas.⁵

Singh et al¹ reported 32 cases of cystic lymphangiomas in children; only 1 of these was located in the scrotum. Loberant et al⁶ estimated that <50 cases of scrotal cystic lymphangiomas have been reported up until 2002.⁶ The clinical diagnosis of lymphangioma is less challenging in its common locations. However, imaging is required for a diagnosis if it is in an unusual location.⁷ Hurwitz et al² reported 7 cases of scrotal cystic lymphangioma over a 10-year period, all of which were misdiagnosed preoperatively. Four of the cases recurred because of incomplete excision. For this reason, preoperative imaging is mandatory to define the exact nature and extent of the lesion. The use of color Doppler US is the simplest investigation and is often sufficient to provide a definitive diagnosis.⁷ Lymphography can detect only those lesions that communicate with the lymphatic system, and cystic lymphangiomas do not communicate.⁷

Gray-scale US generally shows a multicystic extra-testicular mass with internal septae. Internal echoes in the cysts are due to hemorrhage and/or debris.^6,8 In the case reported here, color Doppler showed vessels within the septae, a finding that would not be expected in an organized pyocele or hematocele, which may otherwise have a similar sonographic appearance.⁶ To the best of our knowledge, this is only the second case of scrotal lymphangioma that showed presence of blood flow in the septa.⁶ Loberant et al⁶ suggested that the presence of high-resistance arterial waveforms in the septa of scrotal lymphangioma indicates the benign nature of the lesion. Other entities that should be included in the differential diagnosis are large epididymal cyst and epididymal cystic lymphangioma, since they may have similar features but are confined to epididymis.⁹ In the case of varicocele, the anechoic, serpiginous channels will fill with color flow while the patient performs the Valsalva manuever and, especially, when the patient stands upright. Rhabdomyosarcoma may present as a complex solid-cystic scrotal mass, with blood flow within the solid components on color Doppler imaging.⁸

The treatment of cystic lymphangioma of the scrotum consists of surgical excision of the entire mass, including the overlying skin. The excision should be as complete as possible because of the frequent incidence of recurrence when lymphomatous tissue is left behind. Other treatment modalities (such as injection of sclerosing agents, extensive fulguration, and topical cryotherapy) have been tried without much success.⁷

CONCLUSION

Cystic lymphangioma of the scrotum, although a rare condition, should be considered in the differential diagnosis of a cystic extratesticular scrotal mass in a child. Familiarity with the sonographic and color Doppler features of scrotal lymphangioma is helpful in establishing the cause of extratesticular scrotal fluid collections in infants and children.

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