Umbilical granuloma

A 2-month-old male infant presented with a reddish polypoidal mass lesion at umbilicus (Figure 1) with occasional bleeding. Parents noted the swelling after the umbilical cord fell off at end of 1 month. It was stable in size since then.

Ultrasound with linear (2-10Hz) probe shows a well-defined polypoidal hyperechoic solid mass at the umbilicus in axial (Figure 2) and craniocaudal extent (Figure 3). The lesion on colour Doppler shows a prominent vessel arising from the base the supplying the overlying mass (Figure 4) and shows predominant arterial flow on spectral Doppler (Figure 5). The rest of the mass does not show vascularity and no deeper extension of lesion is seen.

Background

Umbilicus is associated with the embryologic development of the gastrointestinal tract, urinary tract, and umbilical vessels. Common pediatric umbilical masses include omphalomesenteric duct (OMD) remnants (including enteric duplication cysts), umbilical granulomas, umbilical hernias, urachal remnants, benign soft tissue masses like epidermoid cysts, hemangiomas, and/or benign soft tissue tumours [1,2]. Few malignant tumours can also arise from urachus like rhabdomyosarcoma, leiomyosarcoma, inflammatory myofibroblastic tumour, neuroblastoma and yolk sac tumour [3].

Umbilical granulomas are reported as the most frequent lesion originating from umbilicus in newborns with few studies quoting incidence to be 1 in 500 newborns [4]. They develop when fibromuscular ring of the umbilicus closes and the umbilical cord sloughs. This ring is covered anteriorly by skin and posteriorly by peritoneum. After cord detachment, the ring undergoes incomplete epithelialization and a beefy red granulation tissue to be visible after the first few weeks of life [1,2].

Clinical Perspective

Many masses at umbilicus can appear as reddish nodular masses and often have a reddish blood-stained or serous discharge, which is a cause of concern for parents. They need to be differentiated because of differences in management of these conditions. Ultrasound is the first modality for imaging in infants to differentiate these pathologies.

Imaging Perspective

Ultrasound can suggest a possible diagnosis of umbilical granuloma with its superficially located solid fleshy mass on ultrasound with prominent fibrovascular core which suggests granulation tissue formation and is a normal stage in wound healing. It represents division and migration of endothelial cells to form a rich bed of new capillaries [2]. Colour Doppler is useful to demonstrate these vessels.

Among the differentials, umbilical polys are deep seated and often cystic with thick wall and are hypo-vascular in nature and represent OMD remnant consisting of intestinal/gastric mucosa or pancreatic tissue at the umbilicus. It is difficult to distinguish other types of OMD cysts as most of them appear as cystic lesions with internal echoes [1,2].

Urachal cysts result from incomplete regression of the allantoic duct (urachus), a second ductal structure in the cord that connects to the embryonic bladder [5]. It also appears as a cystic lesion on ultrasound and can occur anywhere along the course from dome to bladder to umbilicus and can be associated with fistulous communication with bladder or a sinus communicating with cyst.

Epidermoid cysts should also be considered in the differential diagnosis. They can contain keratin and desquamated squamous cells. On ultrasound onion skin-like or target-like appearance with varying internal echogenicity can be seen. They rarely present with a cystic appearance, as in umbilical polyps, or with the hypervascularity observed in umbilical granulomas [6].

Malignant tumours are mostly solid tumours with aggressive nature and large intraabdominal component with or without adjacent infiltration and signs of metastases. Most of them require histopathological evaluation [3].

Outcome

Umbilical granulomas are treated with application of silver nitrate. If the granuloma is too large or if treatment with silver nitrate fails, the lesion may need to be excised surgically. In our patient, topical silver nitrate lead application led to subsequent decrease in lesion size over a period of one week.

All the other OMD remnants including umbilical polyp and other differentials need surgical excision.

Take Home Message / Teaching Points

Reddish polypoidal mass lesion at umbilicus with discharge needs ultrasound evaluation so as to differentiate umbilical granulomas from umbilical polyps and other differentials so as to decide the management.

Written informed patient consent for publication has been obtained.