Spontaneous partial regression of a microcystic jejunal mesenteric lymphangioma and a proposed management algorithm

Abstract

Mesenteric lymphangiomas are relatively rare, with clinical symptoms ranging from an asymptomatic presentation to an acute abdomen. The natural history and biological behaviour of this entity can range from slow indolent lesions to aggressive tumours with a risk of malignant transformation. Spontaneous regression of a mesenteric lymphangioma is rare. We herein report a case of a jejunal mesenteric lymphangioma that was initially detected incidentally in an asymptomatic patient with a subsequent sudden increase in size with resulting surrounding mass effect after 9 months and a spontaneous partial regression at surgical resection. Our case is the first reported case which outlines a period in the natural history and evolution of microcystic mesenteric lymphangioma, illustrating the sudden enlargement likely attributable to spontaneous and self-limiting haemorrhage and subsequent partial regression at surgical resection. We thenceforth propose a possible management algorithm for adult patients with mesenteric lymphangiomas.

Background

Definition

Lymphangiomas of the mesentery are relatively rare benign tumours in which the majority are considered to be lymph vessel anomalies.¹ Histologically, they are characterised by the proliferation and enlargement of lymphatic spaces that are surrounded by thin-walled endothelial cells.^{1 2}

Epidemiology

Lymphangiomas occur mainly among paediatric patients in the first few years of life and are far less commonly discovered in adults.³ Approximately 90% of all lymphangiomas occur in the head, neck and axillae, while less than 5% are found intra-abdominally.⁴ Within this small subgroup of intra-abdominal lymphangiomas, they are reported to most commonly occur in the small bowel mesentery—accounting for 70% of the distribution—followed by retroperitoneum, omentum and the mesocolon.^{5 6} The incidence of a mesenteric lymphangioma is estimated to be 1 in 1 000 000 and less than 200 cases have been described in the literature.⁷

‘Spectrum and biological behaviour’ of small bowel mesenteric lymphangiomas

Clinical manifestations of small bowel mesenteric lymphangiomas can be protean. The spectrum of clinical presentation can range from an asymptomatic presentation to a non-specific abdominal discomfort, a palpable abdominal mass, a bowel obstruction or even an acute abdomen.⁸

While the exact natural history of this condition remains unclear, the biological behaviour has been known to range from slow indolent lesions to aggressive tumours with a risk of malignant transformation.^{9 10} Hence, surgical resection is widely accepted as the primary treatment even among asymptomatic patients.

We herein report a rare case of jejunal mesenteric lymphangioma, which was incidentally detected in an asymptomatic patient initially, with a subsequent sudden increase in size with resultant surrounding mass effect after 9 months and spontaneous partial regression at surgical resection.

Case presentation

A 68-year-old Chinese male patient was admitted for left hemispheric syndrome secondary to a left middle cerebral artery infarct. During the admission, he developed Enterococcus faecalis bacteraemia due to urosepsis (with urine cultures also isolating the same pathogen).

As part of the septic workup, a CT scan of the chest, abdomen and pelvis incidentally found a lobulated fluid density lesion in the right flank of the abdomen extending from the subhepatic region along some small bowel loops into part of the mesentery. The differential diagnoses of a cystic tumour arising in the mesentery include both malignant and benign tumours. Benign causes would include lymphangioma and foregut duplication cysts, and malignant causes would include necrotic neoplasms and germ cell tumours such as teratomas. As the lesion had a septated cystic appearance with a paucity of solid components, it was most suspicious for a small bowel mesenteric lymphangioma. An MRI of the abdomen (figure 1) confirmed these findings, showing a defined cystic structure with numerous mild internal septations, measuring 65×35×120 mm. There was no fluid level or any large solid-enhancing mural nodule.

Figure 1.

MRI abdomen and pelvis (T2-weighted coronal sequence): showing a well-defined, large, thinly septated, cystic lesion (red arrow). No fluid level or large solid-enhancing mural nodule is seen.

As there was no evidence of any mass effect or complications arising from this lesion, the mesenteric lymphangioma was managed conservatively. To further assess for complications, a gastroscopy and colonoscopy were performed, which showed no intraluminal extension of the lesion.

The patient defaulted follow-up initially but represented 9 months later with central abdominal pain across a period of 1 week, becoming more constant and severe over the course of 2 days prior to presentation. He had nausea, was still able to pass flatus and his vital signs were normal. On physical examination, there was generalised abdominal tenderness and occasional voluntary guarding. Blood investigations revealed that the patient’s white cell count, C-reactive protein and lactate levels were within normal ranges.

A contrast-enhanced CT scan demonstrated an interval increase in size of the mesenteric lesion, which was extending from the right hemipelvis to the central abdomen. There was mass effect causing displacement and mild twisting of the small bowel coupled with encasement of the mesenteric vessels which resulted in small bowel and mesenteric congestion. While there was no definite solid component or adenopathy noted, the possibility of a malignant transformation could not be excluded. However, the slow growth of the lesion over the 9 months is another factor favouring the diagnosis of a mesenteric lymphangioma. An MRI scan confirmed the enlargement of the lobulated septated cystic structure, measuring 47×92×168 mm (figure 2).

Figure 2.

MRI abdomen and pelvis (T2-weighted coronal sequence) performed 9 months later: showing a significantly larger lobulated septated cystic mass (red arrow).

Nevertheless, the patient’s symptoms subsided promptly, and his abdomen was soft and non-tender. His plasma lactate and base excess levels were within normal range. In view of the clinical and radiological findings, surgical resection for the mesenteric lesion was performed electively 3 weeks later.

Intraoperatively, the mesenteric lymphangioma was localised to a 5 cm segment of jejunal mesentery and appeared to have partially regressed. It was a multilobulated soft cystic mesenteric mass, with some parts partially inflamed and thrombosed. The lesion was situated adjacent to and slightly encroaching the corresponding segment of jejunum, where the small bowel itself appeared grossly normal (figure 3). The mesenteric lymphangioma and the corresponding jejunal segment were resected and a primary anastomosis was performed. The patient thereafter made an uneventful postoperative recovery.

Figure 3.

Showing partial regression of the mesenteric lymphangioma with some parts of the mesentery appearing partially inflamed and thrombosed. The small bowel appears grossly normal.

Histology confirmed a 43×41×20 mm mesenteric lymphangioma consisting of multiple thin-walled dilated cystic spaces encroaching the small bowel wall (figure 4). The cystic spaces ranged from 2 to 4 mm in size (hence categorised as a microcystic lymphangioma) and were lined by flattened epithelium and filled with serosanguinous fluid (figure 5). The lining epithelium of the lymphatic spaces is highlighted with D2-40 (figure 6). CD68 highlights histiocytes and calretinin stains mesothelial cells. Recent and old haemorrhages were seen. The cystic spaces spanned the entirety of the mesenteric fat and did not extend to the overlying serosa. The small bowel wall was intact, and its mucosa was normal.

Figure 4.

H&E stained section showing relation of lymphangioma in the small bowel (original magnification ×5).

Figure 5.

H&E stained section showing cavernous cystic spaces with endothelial lining ranging from 2 to 4 mm in size (original magnification ×100).

Figure 6.

D2-40 immunohistochemical staining highlighting the lymphatic endothelial cells (original magnification ×100).

Outcome and follow-up

The patient is well and stable. He remains asymptomatic with no signs of disease recurrence at 9 months postoperative follow-up.

Discussion

Traditional Wegner classification

In 1877, Wegner traditionally classified lymphangiomas into three histological subtypes: 1. lymphangioma simplex (capillary), which is not commonly found intra-abdominally; 2. cavernous lymphangioma, which, while still rare, is more commonly found than lymphangioma simplex intra-abdominally and may undergo malignant transformation and 3. cystic lymphangioma, which is almost always benign.² Lymphangiomas can also be classified into three subgroups according to the size of the cysts: 1. microcystic, which are composed of cysts measuring less than 2 cm³ in volume; 2. macrocystic, which are composed of cysts measuring more than 2 cm³ in volume and 3. mixed, which contain both microcystic and macrocystic components.¹¹

Pathogenesis and clinical features

The pathogenesis of lymphangiomas remains controversial. The most well-established theory is the ‘blind sac’ hypothesis, which postulates that a failure of communication between the lymph sacs and venous drainage causes them to proliferate and dilate.^{12 13} Other aetiologies have also been described, and it is reported that these malformations may also occur after abdominal trauma, lymphatic obstruction, inflammatory processes and surgical or radiation therapies.⁸

The clinical features of a mesenteric lymphangioma can be rather non-specific. However, reports have documented abdominal pain, vomiting, abdominal distension, a palpable abdominal mass or an acute abdomen, which includes symptoms of bowel obstruction, volvulus, bleeding and infection.^{9 14}

Mesenteric lymphangiomas in the jejunal mesentery tend to be located near the mesenteric artery, making them less likely to compress the intestine during the early stages but is at risk of rupture and haemorrhage as they grow much larger. In contrast, mesenteric lymphangiomas in the ileal mesentery tend to be smaller and closer to the ileal wall, making them more likely to cause intestinal compression, bowel obstruction and volvulus.¹⁵ Immunological staining for factor VIII-related antigen, D2-40, calretinin and human melanoma black-45 are essential for diagnosis and distinguishing between lymphangiomas and cystic types of intra-abdominal mesotheliomas.^{2 16}

Management and recurrence rates

The primary and gold standard treatment of lymphangiomas is radical surgical excision even when patients are asymptomatic. This is due to their potential to grow enormously to invade adjacent structures and cause complications, as well as their potential to express malignant change, particularly if they are of the cavernous subtype.^{9 10} Complete resection is also necessary for diagnostic confirmation and recurrence prevention. The overall results of surgical resection are by and large favourable, with reported recurrence rates ranging from 0% to 13.6%, occurring mostly in patients with retroperitoneal lymphangiomas or those who have undergone partial excision; the overall mortality rate in adults and children is 2%.¹⁷

Regression of lymphangiomas

The regression rates of lymphangiomas are reported to range from 1.6% to 16.0%, and these have been reported only mostly in lymphangiomas of the head and neck.¹⁸ While cases of spontaneous regression of intra-abdominal lymphangiomas have been described before, these are uncommon occurrences, with complete regression being relatively rare.^19–21 Regression of lymphangiomas may also occur after an infection.²² In the largest series published on lymphangiomas, Kato et al reported that among 153 patients, spontaneous regression only occurred in macrocystic or mixed-type lymphangiomas and in older patients that were more than 2 years of age.²³ It must be noted however that none of the patients in this particular study had intra-abdominal lymphangiomas. In contrast, spontaneous partial regression was observed in a microcystic-type intra-abdominal jejunal mesenteric lymphangioma in our patient.

Correlation with our patient and sequelae of symptoms

The causative mechanism resulting in the development of the jejunal microcystic lymphangioma in our patient is unclear. Our patient reported no past medical issues prior to admission and had none of the aforementioned risk factors and aetiologies, including lymphatic obstruction or previous irradiation therapies. The presence of recent and old haemorrhages on histology likely correlated with spontaneous haemorrhage characteristic of jejunal mesenteric lymphangiomas, manifesting clinically as acute abdominal pain and radiologically evidenced by sudden enlargement and encasement of mesenteric vessels resulting in venous congestion. Furthermore, the self-limiting nature of this haemorrhage is consistent with the spontaneous resolution of the patient’s symptoms and significant size regression on surgical resection.

Due to the rarity of intra-abdominal lymphangiomas, the uncertainty of their natural history and biological behaviour and the difficulty in obtaining a preoperative histological diagnosis, the question of when to perform surgery or whether it should be performed at all remains debatable. From this case report, we would like to highlight that interval elective surgery from the time of acute presentation may result in a less extensive surgical resection while ensuring adequate margins to prevent future recurrences. With the clinical and radiological evolution of this condition as demonstrated in our patient, there may also be a role for interval scans prior to any elective surgery. Furthermore, with a spontaneous complete regression of the lesion, it is possible that surgery may not be required. We therefore propose a possible management algorithm (figure 7). Certainly, cohort studies with larger numbers and longer follow-ups are needed to draw reasonable conclusions.

Figure 7.

Proposed possible management algorithm of intra-abdominal lymphangiomas.

Learning points.

• Intra-abdominal lymphangiomas are rare entities, and given that spontaneous regression, partial or complete, is possible, there remains the question of when to perform surgery or whether it should be performed at all.

• Spontaneous regression can occur either partially or completely.

• While spontaneous regression was only previously reported in macrocystic and mixed-type lymphangiomas before, spontaneous regression can also occur in microcystic-type lymphangiomas.

• The evolution of a patient’s clinical symptoms may illustrate the natural history and evolution of a microcystic small bowel mesenteric lymphangioma as illustrated in our patient from its incidental discovery to its subsequent presentation with abdominal pain due to a sudden enlargement in size likely from spontaneous yet self-limiting haemorrhage and, finally, partial regression by the time of surgical resection.

• There may be a role for interval scans prior to any elective surgery to be able to achieve less extensive surgical resection while still ensuring adequate surgical margins to prevent future recurrences.