A 41-year-old male patient with uneventful past medical history, presented with a long standing (several years) unusual, painless sensation in his left lumbar region.
The patient was admitted to our institution to study his increased sensation at the left lumbar region.
He underwent the following exams.
Plain film of the abdomen: no morphostructural bone alterations. Some calcification can be seen in the left flank region, apparently inside a roundish abdominal formation compressing the psoas muscle and displacing the distal descending colon medially.
Abdominal ultrasound: large expansive formation (10cm diameter) in the left retroperitoneal space characterized by a mixed structure with coarse calcification inside and signs of lesional vascularization.
Computed Tomography (CT) :CT scan before administration of Iodinated contrast shows a rounded retroperitoneal mass lesion compressing the psoas muscle with some calcification. CT scan after administration of Iodinated contrast shows a non homogeneous attenuation and poor contrast enhancement. The mass contains areas of necrosis. Some small lesions in the liver that needed MRI to be characterized.
MRI: Characterized the liver lesions as angiomas. It also exclude the presence of fatty tissue into the retroperitoneal mass
Retroperitoneal primitive tumors are a heterogeneous group of tumors that originate in connective, vascular, nervous or muscular tissues, or in embryonic residues; they are usually malignant (85%). They mainly affect men, 40-60 years of age.
Generally these tumors grow slowly and are usually of insidious onset; for this reason they are often very large at the time of diagnosis (in 50% of cases they have a diameter greater than 10cm). In rare cases they are metastatic at the moment of diagnosis.
Malignant fibrous histiocytoma (MFH) is one of the most common types of soft tissue sarcomas in adults. Its incidence increases with age. The majority of patients are older than 50 years of age.
There are four major variants of MFH recognized today: storiform-pleomorphic (the most common), myxoid, giant cell and inflammatory. The myxoid type of MFH (also known as myxofibrosarcoma) accounts for one-third of all MFH cases. It was first described by several authors in the late 1970s, and was identified based on its gross distinct gelatinous appearance, with a variable amount of myxoid stroma adjacent to the cellular areas visible microscopically.
The most common primary sites are the extremities (77%), trunk (15%) and retroperitoneum (8%). Treatment is usually resection and radiation therapy for local control, supplemented by chemotherapy for prevention of recurrence and treatment of micrometastatic disease.
Factors believed to favorably influence recurrence rates and metastasis in myxoid MFH include: small size, superficial location, increased proportion of themyxoid component and low grade. The patient underwent surgery to remove the mass.
Histology shows a malignant fibrous histiocytoma
At radiological analysis, MFH usually manifests as a well-defined, smooth or lobular soft tissue mass. CT usually reveals heterogeneous attenuation and enhancement. Large masses, which usually contain areas of hypodensity, are suggestive of malignancy. Large areas of necrosis, which develop especially in leiomyosarcomas and malignant hisiocytomas, cause the CT numbers to drop to the water range. The attenuation value reflects the nature of the tumor tissue, so it can help to distinguish MFH from fatty tumors like lipomas and liposarcomas.
Although CT is nonspecific in many cases, a number of CT features and clinical findings may suggest specific diagnoses when present: presence of calcification in malignant fibrous histiocytoma; presence of fat in a mass lesion of heterogeneous density in liposarcoma; large regions of necrosis in Leiomyosarcoma (but also other tumor types may contain necrotic regions); calcified tumor in a child in neuroblastoma; hypervascularity of hemangioma and hemangiopericytoma; catecholamine excess and paraaortic location in paraganglioma; homogeneous, low density of neurofibroma; homogeneous, fat density of lipoma; and characteristic mixed components of teratoma.
A knowledge of the range of CT appearances and various clinical settings for this rare group of neoplasms should assist the radiologist in making an appropriate CT interpretation when one of them is encountered.
Malignant fibrous histiocytoma
Based on the provided X-ray, CT, and MRI images, there is a large soft tissue mass in the left retroperitoneal region adjacent to the psoas muscle (left lumbar area):
Considering the patient's middle-aged male status, long disease course, large retroperitoneal mass, and imaging features, the following differential diagnoses should be considered:
Given the tumor’s size, morphology, and pathological features (indicated in the report as Malignant Fibrous Histiocytoma), the diagnosis of MFH/Myxofibrosarcoma is most consistent.
Based on the patient’s medical history, imaging findings, and postoperative pathological results, the final diagnosis is:
Malignant Fibrous Histiocytoma (MFH)
After surgery and adjuvant treatments, rehabilitation exercises should be gradually introduced based on the patient’s physical condition and local wound healing. Attention should be paid to the following principles:
Reference the FITT-VP principle (Frequency, Intensity, Time, Type, Progression, Volume):
For example, in the early postoperative period, simple bedside activities may be performed under the guidance of a physician or rehabilitation therapist, gradually transitioning to indoor walking and light resistance exercises to improve core and lower-limb muscle strength. As recovery advances, moderate water-based rehabilitation, low-intensity treadmill exercises, or stationary cycling may be introduced.
This report is based on the provided medical history and imaging data for reference purposes only and does not replace an in-person consultation or treatment plan by professional physicians. Actual diagnosis and treatment should be determined by a comprehensive evaluation from specialized clinical doctors.
Malignant fibrous histiocytoma
