Diagnosis and Treatment of Inflammatory Myofibroblastoma in Children and Adolescents
Inflammatory myofibroblastoma (IMT) is a rare type of intermediate tumor with malignant potential that predominantly affects children and young adults. Although IMT can arise from various organs, the most common sites of origin are the lungs, abdomen/pelvis, and retroperitoneum. These tumors are believed to develop through a benign inflammatory process, although some exhibit malignant behavior or undergo malignant transformation. Due to the rarity of IMT, there are no uniform guidelines for its clinical management. Surgery is currently the first-line treatment, but other therapeutic options may be considered when complete excision is not feasible. This article summarizes the clinical data of 16 pediatric patients diagnosed with IMT, reviews the literature, and shares insights into the diagnosis and treatment of this disease.
Clinical Presentation and Demographics
The study included 16 patients aged 18 years or younger who were diagnosed with IMT between 2013 and 2018. The mean age at presentation was 8.9 years, with a range of 0.9 to 18.0 years. The male-to-female ratio was 1:1. The mean follow-up duration was 2.3 years, with a range of 0 to 4.7 years. Two patients were lost to follow-up.
The clinical manifestations of IMT varied depending on the tumor location. Intraperitoneal IMT presented with symptoms such as abdominal distension, abdominal pain, palpable mass, blood stool, fever, yellowed skin and mucous membranes, and other digestive symptoms. Pulmonary IMT was associated with cough, expectoration, dyspnea, and chest pain. Bladder IMT manifested as hematuria, while maxillofacial and cervical IMTs were associated with swelling and palpable masses. Additionally, seven patients presented with systemic symptoms, including fever, anorexia, and weight loss.
Laboratory and Imaging Findings
Six of the 16 patients (38%) had an elevated white blood cell count, while 11 patients (69%) exhibited hypochromic microcytic anemia. Non-specific tumor markers were detected in 12 patients (75%). Computed tomography (CT) was the primary imaging modality used to evaluate the tumors. In 11 cases, CT revealed tumors with clear borders, which were subsequently excised completely.
Surgical Treatment and Outcomes
Surgical resection was the mainstay of treatment for IMT in this cohort. The procedures performed included lung lobectomy (left lung in one case, right middle and lower lobe in one case), excision of a left superior mediastinum tumor and partial rib (one case), total excision of the mass with adjacent bowel (three cases), partial cystectomy (two cases), and total excision of neck masses (three cases). Nine of the 11 patients who underwent complete excision survived without recurrence. One patient was lost to follow-up, and one died of a chest infection one month postoperatively.
In cases where complete excision was not possible due to tumor invasion of adjacent tissues and organs, palliative surgical excision was performed. For example, one patient with a left lung IMT that invaded the mediastinal macrovascular structure received regular chemotherapy after palliative excision and remained tumor-free. Another patient with omental IMT experienced a recurrence after palliative resection but remained tumor-free after subsequent chemotherapy. A patient with rectal IMT had two postoperative recurrences treated surgically and remained alive but not tumor-free. In a particularly complex case, a liver IMT that invaded all three hepatic hila was treated with complete tumor removal and autologous orthotopic liver transplantation. One patient with pancreatic head IMT refused further treatment after a puncture biopsy and was lost to follow-up.
Adjunctive Therapies
In addition to surgery, various adjunctive therapies were employed based on the clinical scenario. Chemotherapy, immunoregulatory therapies, corticosteroids, radiotherapy, non-steroidal anti-inflammatory drugs, and other treatments were considered when complete resection was not feasible. Three patients with mediastinal or abdominal vital visceral invasion achieved incomplete resection, and two of these patients received regular chemotherapy using the AVCP regimen (pirarubicin, vindesine, cyclophosphamide, and cis-platinum complexes) or the IEV regimen (etoposide, ifosfamide, and leurocristine). Chemotherapy led to reductions in the residual tumor shadow on CT images. All 16 patients received anti-inflammatory therapy. Two cases of ALK-positive disease were detected by fluorescence in situ hybridization, and crizotinib was administered. The effects of this treatment require further study.
Recurrence and Follow-Up
The recurrence rates for IMT vary depending on the tumor location, with less than 2% for lung tumors and up to 25% for extrapulmonary lesions. Most recurrences develop within one year after the initial surgery. Distant metastasis is rare, occurring in less than 5% of cases. Complete tumor excision with clear surgical margins during the initial surgery is the most important factor in preventing recurrence. In this study, 13 of the 16 patients were followed up, with a survival rate of 81%. All surviving patients underwent surgical treatment, and 12 remained in complete remission at the last evaluation. One patient survived with partial remission, and two were lost to follow-up. One patient died due to poor perioperative management of inflammation. None of the surviving patients exhibited deterioration or distant metastasis during follow-up.
Imaging for Recurrence and Metastasis
Given the potential for malignancy in IMT, regular imaging is recommended to detect recurrence and metastasis. CT and magnetic resonance imaging (MRI) examinations are advised at 3 months, 6 months, and 1 year after resection. Subsequently, annual color Doppler ultrasound and CT or MRI examinations are recommended.
Conclusion
Inflammatory myofibroblastoma is a rare tumor with a broad spectrum of clinical presentations and behaviors. While most cases in children are benign, the potential for malignant transformation necessitates careful management. Surgical resection remains the primary treatment, with complete excision offering the best chance of cure. Adjunctive therapies, including chemotherapy and targeted treatments, play a crucial role in cases where complete resection is not possible. Regular follow-up with imaging is essential to monitor for recurrence and metastasis. The experiences shared in this study contribute to the growing body of knowledge on the diagnosis and treatment of IMT in pediatric patients.
doi.org/10.1097/CM9.0000000000000176
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