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| CASE REPORT |
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| Ahead of print publication |
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Fibromatosis mimicking relapse of a neuroendocrine tumor at 68Ga-DOTATOC positron-emission tomography/computed tomography
Elena Trevisi1, Ivan Facilissimo2, Stefano Taraglio3, Maria Pia Brizzi1
1 Department of Oncology, University of Turin, San Luigi Gonzaga Hospital, Orbassano, Italy
2 Department of Oncology, San Giovanni Bosco Hospital, Torino, Italy
3 Unit of Pathology, San Giovanni Bosco Hospital, Torino, Italy
| Date of Submission | 26-Sep-2019 |
| Date of Acceptance | 10-Jan-2020 |
| Date of Web Publication | 07-Nov-2020 |
Correspondence Address:
Elena Trevisi,
Department of Oncology, San Luigi Gonzaga Hospital, Regione Gonzole, 10, 10043 Orbassano
Italy
 Source of Support: None, Conflict of Interest: None DOI: 10.4103/jcrt.JCRT_802_19
Mesenteric fibromatosis (desmoid tumor) is a locally aggressive fibroblastic lesion, characterized by a high recurrence rate that makes treatment challenging. Currently, there is no evidence-based treatment approach. We report the case of a female patient with a history of neuroendocrine tumor, who underwent 68Ga-DOTATOC positron-emission tomography/computed tomography (PET/CT), showing increased focal abdominal uptake suggestive of disease relapse. Histological examination revealed typical findings of fibromatosis. These findings indicate the expression of staining for somatostatin receptors (SSTRs) on fibromatosis cell surface and suggest to include fibromatosis among the potential causes of false-positive results at 68Ga PET/CT. Moreover, SSTRs expressed in desmoid tumors could be further investigated as a therapeutic target. Keywords: 68Ga-DOTATOC positron-emission tomography/computed tomography, desmoid tumor, mesenteric fibromatosis, neuroendocrine tumor, somatostatin receptor
How to cite this URL:
Trevisi E, Facilissimo I, Taraglio S, Brizzi MP. Fibromatosis mimicking relapse of a neuroendocrine tumor at 68Ga-DOTATOC positron-emission tomography/computed tomography. J Can Res Ther [Epub ahead of print] [cited 2020 Dec 3]. Available from: https://www.cancerjournal.net/preprintarticle.asp?id=300199 |
| > Introduction | |  |
Mesenteric fibromatosis (MF) is a sporadic mesenchymal neoplasm of the small bowel mesentery that arises from myofibroblasts. Despite its benign nature, MF is characterized a locally aggressive behavior and a high recurrence rate after surgery. Currently, there is no established evidence-based diagnostic and therapeutic approach.
We report the case of a MF mimicking a neuroendocrine tumor (NET) relapse in a patient with a history of NET, due to an increased uptake at 68Ga-DOTATOC positron-emission tomography/computed tomography (PET/CT).
| > Case Report | | |
An 82-year-old woman underwent duodeno-cefalo pancreasectomy for a well-differentiated NET of Vater's papilla and showed no signs of disease relapse in the next 2 years. For an increase in serum chromogranin A level, a computed tomography (CT) scan was performed, showing a focal mesenteric lesion consistent with a recurrence of the previous NET.68 Ga-DOTATOC PET/CT showed a focal area of abdominal uptake suggestive for localization of NET [Figure 1]. The patient underwent excision of the abdominal lesion, which was consistent at the histological examination with a low-grade mesenchymal neoplasm; morphological and immunohistochemical features were compatible with an abdominal fibromatosis. Subsequent CT scan showed multiple small mesenteric nodules consistent with MF recurrence. Immunohistochemical staining for estrogen and progesterone receptors was negative, where weak staining for somatostatin receptors (SSTRs) was found [Figure 2]. No further treatment was started for patient's decision. | Figure 1: 68Ga-DOTATOC positron-emission tomography/computed tomography scan: Transaxial images (a: Computed tomography; b: Positron-emission tomography; c: Fusion) and three-dimensional positron-emission tomography image (d: Maximum intensity projection) shows a radiopharmaceutical uptake of low intensity at the level of abnormal abdominal tissue
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 | Figure 2: Immunohistochemistry shows a weak expression of somatostatin receptors 2A and somatostatin receptors 5 both in neuroendocrine tumor and in desmoid tumor, consistent with positron-emission tomography finding
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68 Ga-PET/CT has recently emerged as the best nuclear medicine tool for the diagnosis and staging of well-differentiated NET.[1] According to a recent meta-analysis, a pooled sensitivity of 93% and a pooled specificity of 96% have been reported for 68 Ga-PET/CT, higher than for somatostatin receptor scintigraphy (SRS, Octreoscan®).[2] However, even for 68 Ga-PET/CT some cases of false-positive uptake have been described, in both physiological conditions, for example, uptake in the spleen, kidneys, adrenal, pituitary glands, and pancreatic head, and pathological ones, for example, inflammation, osteoblastic activity (degenerative bone disease, fractures, and vertebral hemangioma), splenosis, and benign meningioma.[3]
Desmoid tumors are rare benign neoplasms that can be divided into extra- and intra-abdominal types MF. MF is a rare sporadic mesenchymal neoplasm of the small bowel mesentery that arises from myofibroblasts. Although MF grows slowly without metastatic potential, its unpredictable behavior, propensity for progressive infiltration, and local invasion make treatment challenging. Currently, there is no established evidence-based treatment approach.[4] High local recurrence rates, despite apparently complete resection, have reduced the popularity of surgical resection as initial management. Several drugs have been used in the treatment of MF, including hormonal therapy (e.g., tamoxifen and toremifene), nonsteroidal anti-inflammatory drugs, cytotoxic chemotherapeutic agents, and tyrosine kinase inhibitors (e.g., imatinib, sorafenib, and pazopanib).[5],[6] Magnetic resonance represents the gold standard imaging modality for planning management and detecting disease progression and postoperative recurrence.
This report of the first MF case with increased uptake on 68 Ga-DOTATOC PET/CT implies the cell surface expression of SSTRs by the fibromatosis cells and particularly of SSTR2 and SSTR5 for which 68 Ga-DOTATOC has a predominant affinity. This observation is consistent with previous reports referring to the findings of conventional SRS showing enhanced tracer uptake in desmoid tumors.[7],[8] Further data are needed to better define the potential diagnostic role of SSTR–imaging in deep fibromatosis. SSTRs expressed in desmoid tumors could be further investigated as a therapeutic target since they could allow the selection of patients with the progressive, symptomatic, or recurrent disease for biological therapy or peptide receptor radionuclide therapy. Finally, MF could mimic NET on 68 Ga-PET/CT; hence, it should be included among the possible causes of false-positive.
Although this report refers to a single case, it is important to remember that, as regards rare diseases such as NETs and desmoid tumors, even case reports could be of relevance for the assessment and management of affected patients.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
| > References | | |
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| 8. | Leithner A, Gapp M, Radl R, Pascher A, Krippl P, Leithner K, et al. Immunohistochemical analysis of desmoid tumours. J Clin Pathol 2005;58:1152-6. |
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