Misdiagnosis of scrotal and retroperitoneal lymphangioma in children

The patient’s medical history was not detailed. Lymphangiomas that present with bleeding and swelling may easily be confused with incarcerated inguinal oblique hernia. However, a detailed medical history may reveal a history of oblique hernia in children with an incarcerated inguinal oblique hernia, while children with a bleeding lymphangioma may have a history of trauma. Doctors should also be alerted to the possibility of lymphangioma in patients with recurrence after an inguinal oblique hernia or hydrocele.

Inadequate physical examination. In Case 2, despite the detection after exercise of a soft cystic mass that disappeared completely on squeezing, physical examination of the abdomen was not carried out and the mass was therefore misdiagnosed as a hydrocele. Abdominal scrotal lymphangiomas do not usually adhere to the skin and are soft and fluctuating with clear boundaries, showing positive results. However, transillumination could not be carried out in Case 3. In addition, infected or bleeding lymphangiomas may produce negative transillumination results. Some details of examinations are also helpful but may be easily overlooked, e.g., if the tension of the mass decreases after repeated compression, or stretching of the testicle or spermatic cord to observe significant changes in the mass may suggest that the mass is a hydrocele. Careful physical examination can thus help to avoid misdiagnosis.

Limitations of ultrasound examination. Most patients underwent ultrasound examination within 3 months before surgery, but the results were not sufficiently accurate. If the lymphangioma was limited to the scrotum and inguinal area without protruding into the abdominal cavity (e.g., Case 1), ultrasound suggested a cystic mass and misdiagnosed it as a hydrocele. In addition, if ultrasound fails to detect if the mass extends into the abdominal cavity at the inner ring orifice, or if abdominal ultrasound is not performed, it can also lead to misdiagnosis of lymphangiomas. In some cases, such as Case 3 and in some emergency cases, preoperative ultrasound cannot be completed to determine the presence of incarceration of the intestines or other features such as time constraints, leading to a misdiagnosis of incarcerated inguinal hernia.

Lymphangioma originates from the mesoderm and represents a congenital malformation of vascular development. It is not a ‘real’ tumor, but rather a benign lesion composed of multiple expanded lymphatic cysts formed by the abnormal development of the lymphatic system during the embryonic period. Lymphangiomas are more common in children, with about 90% diagnosed before the age of 2 years old. The incidences are equal between males and females [14, 15]. The pathophysiology of lymphangioma was first proposed by Whimster in 1976, who divided it into three types: capillary lymphangioma, cavernous lymphangioma, and cystic lymphangioma [16]. Cystic lymphangiomas mostly occur in the head, neck, and armpits (95%) and are soft, nonpulsatile, painless lumps. The surface skin is usually normal, but can have a bluish tint or pink vesicles resembling capillary malformations in some patients [17]. Lymphangiomas in the retroperitoneum, scrotum, and inguinal areas are rare. Singh et al. reported 32 cases of cystic lymphangioma in children, among which only one was in the scrotum [17]. In the early embryonic stage, the peritoneum of the lower abdomen in males forms a protrusion (processus vaginalis) towards the inguinal region and extends along the inguinal canal to the bottom of the scrotum. If the processus vaginalis is not closed, a lymphangioma in the abdominal cavity can reach the scrotum through the inguinal canal, and is thus often misdiagnosed as an indirect inguinal hernia, hydrocele, testicle torsion, or varicocele [18].

Painless scrotal masses are usually benign, but a few are malignant, such as sarcomas [13]. Scrotal lymphangiomas are uncommon benign masses of the scrotum caused by inadequate drainage of isolated lymphatic vessels, often presenting as a painless mass that grows gradually over time [3, 19, 20]. Masses in the subcutaneous tissue of the scrotum are not linked to the spermatic cord and may show invasive growth, low tension, and unclear borders and are thus often confused with hernia, hydrocele, and varicocele. If the cyst hemorrhages (spontaneously or after trauma), inflammation occurs, or the balance between lymphatic production and drainage is disrupted, the initially painless mass can suddenly and rapidly enlarge, leading to the acute onset of pain, and potential misdiagnosis of acute testicle torsion [6, 11, 12]. Abdominal scrotal lymphangiomas in children are mostly cystic soft tissue masses. Ultrasound is superior to CT for observing the internal structure of the lesion, which shows subcutaneous mesh occupying behind the testis. Color Doppler flow imaging can also indicate low-velocity venous blood-flow signals on the cyst wall of the scrotal lymphangioma and the inner compartment. If the cyst bleeds, light spots may be seen floating in the dark area [21, 22]. If the doctor notes other symptoms besides scrotal swelling, such as skin abnormalities, a large lump that does not change with body posture and a lobular appearance, ultrasound examination should be performed. If ultrasound examination reveals multilocular cystic masses in the inguinal area or the scrotum, the abdominal and pelvic cavity should be routinely scanned and imaging examinations such as CT or magnetic resonance imaging are also recommended. Puncture can also be used to aid diagnosis: the puncture fluid from lymphangiomas growing in deep soft tissue is light yellow, but this becomes dark red and non-coagulated when combined with internal bleeding [23]. The gold standard for diagnosis is pathological examination. Lymphangiomas are often covered with squamous epithelium, smooth muscle fibers, blood vessels, fat, and lymphoid tissues, and immunohistochemical staining for D2-40 is mostly positive.

Various treatments are available for abdominal scrotal lymphangiomas. Surgical treatment with an inguinal approach is usually the first consideration [24‐26]. During surgery, part of the cyst fluid is aspirated to reduce the tension of the lymphangioma, and the lymphangioma plus the involved skin and tissues are then removed as completely as possible, to prevent recurrence. However, polycystic lymphangiomas are difficult to separate from the surrounding tissues and have a higher risk of bleeding and secondary damage due to the involvement of multiple tissue planes, large size, and high tension. Resection in these cases is usually incomplete, with recurrence rates as high as 35–64%, which could drop to 17–22% with complete resection [27]. Some researchers believe that lymphangiomas in infants may regress spontaneously and small asymptomatic lesions may thus be treated conservatively, while symptomatic lesions need to be managed actively, but preferably using less-traumatic options than surgery [15, 28]. Sclerotherapy, i.e., drug-injection therapy, has become a mainstream option, with a high success rate and low rates of recurrence and complications [29]. If the cyst cannot be completely resected during surgery, it will continue to produce lymphatic fluid, leading to recurrence. Sclerotherapy can thus act on the endothelial cells of blood vessels and lymphatic vessels resulting in luminal embolization and fibrosis, inhibiting lymphatic fluid secretion and reducing the recurrence rate [30]. Uchida et al. noted that lymphangiomas in the inguinal scrotum often infiltrated the surrounding tissues and main structures, such as the vas deferens, making radical surgical resection difficult and increasing the recurrence and morbidity rates. They reported the case of a huge retroperitoneal lymphangioma extending into the scrotum through the inguinal canal, which was successfully treated with OK-432 sclerotherapy, leading to a good outcome [9]. OK-432 is a preparation comprising heat-treated and freeze-dried group A hemolytic Streptococcus penicillin. It has shown good efficacy for lymphangioma [31], but its main adverse reaction is transient fever after injection, with almost 100% of patients experiencing fever within 6 h after injection, lasting for 2–4 days. Most patients also experience serious local reactions such as erythema and swelling of the affected area, while a few may have symptoms of shock. Multiple treatments are therefore required for OK-432 to achieve satisfactory therapeutic effects [32]. Sclerosants such as bleomycin and peplomycin are also widely used. These are cytotoxic antibiotics extracted from Streptococcus, which have demonstrated good effects at low doses; however, complications include interstitial pneumonia and pulmonary fibrosis, with potentially serious consequences [33]. This type of drug is also commonly used in our institution. Three patients in the current study were treated with bleomycin applied to the cysts after surgery, with no occurrence of pulmonary fibrosis during follow-up. Non-selective beta-blockers, such as propranolol, are also commonly used for treating hemangiomas, with proven efficacy for these types of vascular malformations. Regular monitoring of the patient’s heart rate, blood glucose, and blood pressure is required during the treatment process. However, the effectiveness of these drugs for lymphangiomas is not clear, and they are not currently used for the clinical treatment of lymphangioma [34].

Pediatric abdominal scrotal lymphangioma is relatively rare and its clinical symptoms are often difficult to distinguish from those of other conditions such as hydrocele and incarcerated inguinal hernia. The diagnosis therefore depends mainly on a detailed and accurate medical history, careful physical examination, and imaging and pathological tests. Information on peritoneal scrotal lymphangioma is currently lacking. Unilocular peritoneal scrotal lymphangiomas can be resected directly and completely under laparoscopy, while surgical resection of multilocular lymphangiomas may damage the surrounding tissues, such as the vas deferens. In these case, sclerotherapy may be a safe and effective method, resulting in a favorable prognosis.

This study was limited by the small number of cases, which meant that we were unable to verify the conclusions. In the future, we aim to compare the generalized patterns with clinical cases and further validate their practical value.