Gastric Desmoid Fibromatosis – Report of a Rare Mimic of Gastrointestinal Stromal Tumor

Desmoid fibromatosis (DF) involving the gastrointestinal tract is extremely rare. Its intramural location and occasional expansile growth pattern within the bowel wall may mimic a gastrointestinal stromal tumor (GIST). Due to the different disease behaviors and management, it is important to make a correct diagnosis before further treatment. We present an extremely rare case of a gastric DF that on imaging appeared as a discrete intramural mass mimicking a GIST and that was preoperatively correctly diagnosed as a DF based on its cytomorphologic, immunohistochemical, and molecular profiles. The patient is a 71-year-old female who presented with dysphagia and unintentional weight loss. A mass was identified at the gastric fundus. Endoscopic ultrasound-guided fine-needle aspirate (FNA) and biopsy (FNB) were performed. The FNA showed a few small aggregates of cytologically bland spindle-shaped cells with elongated nuclei. The FNB yielded small fragments of tissue composed of bland spindle cells demonstrating nuclear and cytoplasmic immunostain for ?-catenin and focal stain for smooth muscle actin (SMA) and desmin. CD117, DOG1, CD34, caldesmon, S100, cytokeratin AE1/AE3, signal transducer and activator of transcription 6 (STAT6), MUC4, progesterone receptor (PR), and anaplastic lymphoma kinase (ALK) were negative, and MIB-1 showed a very low proliferation activity index. Molecular studies performed by targeted next-generation sequencing showed activating mutations in CTNNB1. These results excluded a GIST and confirmed the diagnosis of a gastric DF. Although it is very rare, DF must be included in the differential diagnosis of discrete intramural gastric spindle cell lesions. A definitive diagnosis can be made preoperatively if enough lesional material is available for appropriate immunohistochemical and molecular studies.

The efficacy and safety of cyclooxygenase 2 (COX2) inhibitors for the treatment of desmoid-type fibromatosis (DF) are unclear. Therefore, we systematically reviewed related literature to assess the efficacy and safety of COX2 inhibitors for DF treatment. We searched pertinent literature between January 1999 and August 2017 to identify relevant studies using the keywords “Fibromatosis, aggressive” and “Cyclooxygenase inhibitors.” Thereafter, we screened and determined the quality of the studies using the Grading of Recommendations Assessment, Development, and Evaluation system and extracted the article data. The critical outcomes selected were the efficacy and adverse effects of COX2 inhibitors. Efficacy was evaluated in terms of clinical benefit when patients showed complete response, partial response, and stable disease. Thirty-one articles were identified from the database search, and one was identified through the reviewers’ manual search. Finally, we retrieved six studies, including three case reports, comprising 89 patients after the first and second screenings. Fifty-three patients were excluded because three studies were reported from the same institution; hence, in total, 36 patients were included. Clinical benefit was noted in 64% of the patients. Three adverse effects were identified from the records of the six extracted studies. The strategy of watchful waiting using COX2 inhibitors with few side effects is weakly recommended for DF, especially DF patients with pain.

Desmoid fibromatosis (DF) involving the gastrointestinal tract is extremely rare. Its intramural location and occasional expansile growth pattern within the bowel wall may mimic a gastrointestinal stromal tumor (GIST). Due to the different disease behaviors and management, it is important to make a correct diagnosis before further treatment. We present an extremely rare case of a gastric DF that on imaging appeared as a discrete intramural mass mimicking a GIST and that was preoperatively correctly diagnosed as a DF based on its cytomorphologic, immunohistochemical, and molecular profiles. The patient is a 71-year-old female who presented with dysphagia and unintentional weight loss. A mass was identified at the gastric fundus. Endoscopic ultrasound-guided fine-needle aspirate (FNA) and biopsy (FNB) were performed. The FNA showed a few small aggregates of cytologically bland spindle-shaped cells with elongated nuclei. The FNB yielded small fragments of tissue composed of bland spindle cells demonstrating nuclear and cytoplasmic immunostain for ?-catenin and focal stain for smooth muscle actin (SMA) and desmin. CD117, DOG1, CD34, caldesmon, S100, cytokeratin AE1/AE3, signal transducer and activator of transcription 6 (STAT6), MUC4, progesterone receptor (PR), and anaplastic lymphoma kinase (ALK) were negative, and MIB-1 showed a very low proliferation activity index. Molecular studies performed by targeted next-generation sequencing showed activating mutations in CTNNB1. These results excluded a GIST and confirmed the diagnosis of a gastric DF. Although it is very rare, DF must be included in the differential diagnosis of discrete intramural gastric spindle cell lesions. A definitive diagnosis can be made preoperatively if enough lesional material is available for appropriate immunohistochemical and molecular studies.

Desmoid type fibromatosis (DF) is a rare, locally aggressive but benign proliferation of fibrous tissue which produces a fibroblastic mass that can cause a wide range of symptoms secondary to mass effect. When resected, these masses most commonly recur in the first 2 years. We present a case of a 33-year-old male with a history of an appendectomy 2 years prior, though his pathology report did not identify inflammation in the appendix, who presented with gradual onset of abdominal pain, and radiographs that demonstrated a large mass in the right lower abdomen. Given his symptoms the mass was resected and pathologic evaluation revealed a desmoid tumor. This case presents a unique possibility of a recurrent desmoid tumor in which the patient’s surgical history and radiographic findings can contribute to the overall management strategy of the patient given the evolving options for treatment of desmoid fibromatosis.

Case description: A 21-year-old healthy female presented with severe left lateral hip pain beginning suddenly two weeks prior. Physical examination revealed zero degrees of left hip external rotation passive range of motion with a firm end feel and pain severity and irritability out of proportion to an expected musculoskeletal presentation. She was referred to her physician with a recommendation for imaging to determine the source of pain and appropriateness of physical therapy. Outcome: Magnetic resonance imaging revealed a foreign mass in her left gluteus medius muscle which biopsy revealed to be a desmoid fibromatosis. Conclusion: This case demonstrates a thorough differential diagnostic process leading to medical imaging referral in a patient with a non-musculoskeletal source of pain. Physical therapists must be diligent in their differential diagnostic process to ensure appropriateness of their treatments or the need for referral.

Objective: The aim of this study was to determine the prognostic factors for recurrence in patients with extra-abdominal desmoid tumors (EDTs) treated surgically. Methods: This single-institution, retrospective study included patients with a histologically-proven extra-abdominal desmoid tumor between 2007 and 2018. The demographic characteristics (age, sex) of the patients, tumor characteristics (region, size, proximity to neurovascular structures, margins), treatment management (surgery and/or adjuvant radiotherapy), and clinical results were analyzed. The effects of these possible prognostic factors on overall and disease-free survival rates and the risk of local recurrence were evaluated. Results: Evaluation was made of 22 patients (16 females, 6 males) with a mean age at diagnosis of 34.7 years (range = 22-76 years). The mean follow-up was 104 months (range = 4.8-168). Tumor localization was in the upper extremity in 4 patients (18.1%), the lower extremity in 11 (50.0%), and the trunk in 7 (31.8%). The mean tumor size (maximum diameter) was 5.2 cm (range = 0.6-13 cm; median = 5.8 cm), and the mean tumor volume was 181.3 ± 531.4 ml. All the 22 patients were treated surgically along with adjuvant radiotherapy (RT) administered to 8 in addition to surgery for the primary treatment of the tumor. Following primary surgery, resection margins were R0 in 11 patients, R1 in 9 and R2 in 2. Local recurrence (LR) developed in 6 patients (27.2%) during the follow-up period. Recurrence-free survival rate (RFS) was 90.9% at one year, 74.1% at 5 years, and 61.7% at 10 years. During the follow-up, no patient died, and distant metastasis was not detected. Tumor length, resection margins, and adjuvant RT were observed to influence the risk of local recurrence (P < 0.05). Conclusion: The results of this study have demonstrated that tumor size ? 5 cm and the presence of microscopic or macroscopic positive surgical margins can increase the risk of LR, and adjuvant RT can reduce the development of LR in the management of EDT.