A giant pregnancy-associated intra-abdominal desmoid tumour: not necessarily a contraindication for subsequent pregnancy

Desmoid tumours are rare mesenchymal tumours, often locally invasive and characteristically associated with a high local recurrence rate after resection. A potential aetiological role for female hormones is indicated. Pregnancy-associated desmoid tumours are almost exclusively located in the abdominal wall. An essential issue is how to counsel women who have had a pregnancy-associated desmoid tumour and subsequently wish to bear a child. A considerably rare case of a patient with a resection of a giant pregnancy-associated, 33 cm in diameter, intra-abdominal desmoid tumour is presented. After a subsequent pregnancy, the patient delivered healthy twins 26 months later. Fifty-four months after treatment, there are no signs of recurrent or second desmoid tumour. Although rarely located in the abdomen, pregnancy-associated desmoid tumours should be included in the differential diagnosis of intra-abdominal tumours detected during or shortly after pregnancy. Based on this case and a few others reported in the literature, subsequent pregnancy does not necessarily seem to be a risk factor for recurrent or new disease.


Background
Desmoid tumour, also called aggressive or desmoid-type fibromatosis, is a rare monoclonal, fibroblastic proliferation. Although histologically benign and unable to give rise to metastases, desmoids are often locally invasive and characteristically associated with a high local recurrence rate after resection. While this fibroblastic disorder may be observed in nearly every part of the body, desmoids occur most commonly in extremities. Intraabdominal location is observed only in a small proportion of patients [1].
Aetiology of desmoid tumours is incompletely defined. Numerous acknowledged factors are associated with their development [1]. Increased incidence occurring during and after pregnancy, as well as following use of oral contraceptives, the preponderance of women of reproductive age in many series, anecdotal reports of spontaneous tumour regression during menopause, expression of oestrogen beta receptor and reports of tumour regression with anti-oestrogen treatment are all factors which indicate a potential aetiological role for female sex hormones [1,2]. Pregnancy-associated desmoids are almost exclusively located in the abdominal wall [2,3]. Herein we report on a young woman with a giant intraabdominal desmoid tumour diagnosed 3 weeks after giving birth and resected soon afterwards. The location of a pregnancy-associated desmoid tumour in the abdomen is unusual. Further, due to hormonal influences, a subsequent pregnancy may theoretically be a risk factor for a second desmoid or recurrent disease. Neither during nor after the subsequent pregnancy was recurrence or development of a second desmoid tumour observed in our case. The literature on this topic is herein reviewed.

Case presentation
A 31-year-old woman presented with persistent abdominal distension 3 weeks after vaginal delivery of a healthy daughter. It had been her first pregnancy. She was breast-feeding her baby. Her medical history was unremarkable and she had had neither trauma nor any abdominal operation in the past. At physical examination intra-abdominal mass was found. Laboratory tests were normal. Computed tomography (CT) and magnetic resonance imaging (MRI) demonstrated a huge solid intraabdominal soft tissue mass, which occupied most of the peritoneal cavity and which had displaced anatomical structures such as the liver, the pancreas and the small and large intestine ( Figure 1). Chest CT showed no evidence of metastatic disease. CT-guided core needle biopsy revealed a mesenchymal, probably myofibroblastic, lesion whose biological behaviour could not be determined.
At laparotomy, a large intra-abdominal mass was observed ( Figure 2). The transversal colon and its mesocolon were stretched over the frontal side of the tumour and fixed to the mass ( Figure 2). While its caudal side was mobile (Figure 3), the cranial side of the tumour was fixed focally to the inferior part of the tail of the pancreas (Figure 4). There was no infiltration of other organs. The tumour with the transverse colon, its mesocolon and a wide rim of the tail of the pancreas was resected en bloc. An end-to-end anastomosis of the ascending with the descending colon was performed. The postoperative course was uneventful. The tumour weighed 6.2 kg and was 33×29×8.5 cm in size. Histological examination demonstrated a mesenteric desmoid tumour ( Figure 5) which had actually infiltrated the transverse colon as well as the surface of the resected part of the pancreas. The tumour appeared to have been excised completely. Immunohistochemical staining for oestrogen receptor alpha and progesterone was negative. No pathology was seen in the resected colon.
The patient did not receive any adjuvant treatment. She became spontaneously pregnant, despite the recommendation that she postpone pregnancy to allow for a 2-year disease-free follow-up period. Nevertheless, she delivered  healthy twins by Caesarean section 26 months after initial treatment for the desmoid tumour. Fifty-four months after resection of the desmoid, she is in excellent condition without any sign of tumour recurrence on abdominal sonography and MRI, or of development of a second desmoid tumour.

Discussion
The enormous tumour size in the present case is noteworthy. Primary desmoids >30 cm in size have only incidentally been reported [4][5][6]. It remains remarkable that the tumour was not observed at routine repetitive sonography during pregnancy. The optimal treatment of desmoids remains difficult to be determined, due to the rarity, the heterogeneity and the very unpredictable natural history of the disease. Therefore, an individualized approach is warranted [1]. Surgical resection has most commonly been used, while radiotherapy, medical treatment and watchful waiting are alternative options [1].
Typically, desmoids arising during or shortly after pregnancy are almost always located in the abdominal wall [2,3]. Such an association with pregnancy has very rarely   been observed in other locations (Table 1). Single cases of desmoid tumour arising in the vulva [7], larynx [8], neck [9] and popliteal space [10] during pregnancy have been described, while only a few cases of pregnancy-associated intra-abdominal desmoids, originating from the retroperitoneum [11], mesentery [12,13] and pelvis [14,15] have been reported. In one report [14], a pelvic desmoid tumour interfered both with normal maturation and delivery of the fetus as well as the patient's ability to void and defecate, prompting surgical intervention at 23 weeks of gestation. Following the resection the patient delivered a healthy full-term baby. In the other pelvic   [15], the tumour obstructed labour, necessitating a Caesarean section and subsequent tumour excision. In our patient, the intra-abdominal desmoid tumour evidently grew rapidly, reaching its enormous dimensions due to hormonal stimulation during pregnancy. The giant tumour had no apparent adverse influence on the fetus and its vaginal delivery, possibly because the desmoid originated from the transversal mesocolon. Although only a few cases have been reported, desmoid tumour should be included in the differential diagnosis of intra-abdominal tumours detected during or shortly after pregnancy. An essential issue is how to counsel women who have been diagnosed with a pregnancy-associated desmoid and subsequently wish to have a child. Only a small number of case reports provide some data regarding this issue (Table 2). During subsequent pregnancy an untreated pregnancy-associated desmoid tumour of the abdominal wall demonstrated volumetric increase of the tumour, necessitating surgical resection in one patient [16], while there was significant regression without treatment in another case [17]. As in the present case, the only three other patients reported with a subsequent pregnancy after surgical treatment for their pregnancyassociated desmoid demonstrated no recurrence or second desmoid tumour [18,19]. Hence, a subsequent pregnancy does not necessarily seem to be a risk factor for recurrent or new disease. Nevertheless, a follow-up period of at least 2 years before planning a subsequent pregnancy may be advisable, since the median time to desmoid recurrence after resection is approximately 1 to 2 years, as is reported in large series [4,[20][21][22].

Conclusions
Although pregnancy-associated desmoid tumours are almost exclusively located in the abdominal wall, desmoid tumour should be included in the differential diagnosis of intra-abdominal tumours detected during or shortly after pregnancy. From the sparse literature data and from the case herein presented it seems that subsequent pregnancy is not necessarily a risk factor for recurrent or new desmoid tumour. Based on the median time to eventual desmoid recurrence after resection, it may be advisable for the patient to allow for a 2-year follow-up period before planning an eventual subsequent pregnancy.

Consent
Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal.