A Kohli MD, RK Gupta MD, H Poptani MD.
We reported on one patient with high-grade soft-tissue sarcomas mimicking traumatic intramuscular hematomas. Patient had an episode of trauma to the extremity, and after initial clinical and imaging evaluations they were considered to have muscular hematomas. The lesions increased in size over time, leading to further evaluations that demonstrated the actual diagnosis. We conducted a retrospective review of the clinical findings, magnetic resonance images, and computed tomography scans to assess characteristics that will help in the differential diagnosis. We conclude that intramuscular hematomas following trauma should be approached with a high degree of clinical suspicion. MRI analysis can be used as an important diagnostic tool, but the results must be seen in the context of the clinical history. MRI is not sensitive or specific enough to rule out malignancy. The diagnosis of a high grade sarcoma must be considered in these patients and any doubt should be resolved with a biopsy.
Sarcomas comprise approximately one percent of malignant tumors and represent a significant diagnostic and therapeutic challenge.14 The incidence of softtissue sarcomas in the United States ranges from 20 to 30 per 1,000,000 persons, approximately 6,000 new cases per year.13 Soft-tissue sarcomas are a heterogeneous group of tumors that arise from tissue of mesenchymal origin and are characterized by infiltrative local growth. The metastatic spread of sarcomas is mainly hematogenous to the lungs, although lymphatic spread may occur. Soft-tissue sarcomas can occur at any site throughout the body.5 Almost 45 percent of all soft tissue sarcomas are found in the extremities, especially in the lower limb. Patients usually present with a complaint of a lump or growth, with or without pain. However, there are some instances in which the patient will present after moderate trauma to the extremity. These cases are very challenging since the injury symptoms and imaging studies could mask the underlying tumor. We present the cases of three patients with high-grade sarcomas who initially suffered moderate traumas to their extremities and were initially diagnosed with intramuscular hematomas by clinical and imaging studies.
A healthy 44-year-old female suffered trauma to her left arm, falling on her outstretched hand while working. After an initial evaluation by her local physician she was diagnosed with a “muscle strain with a concomitant hematoma.” The patient started physical therapy, however there was no improvement of her symptoms and she again consulted the physician a week later. An MRI was then ordered which showed a well-circumscribed mass not attached to the humerus along the lateral border of the left biceps brachii muscle, measuring 14.5 x 6.5 x 5 centimeters, with an intermediate signal in T1, and a high signal in T2. The radiologist and the attending physician interpreted the MRI as a muscular hematoma. Conservative care was ordered with continued physical therapy. Six months after the traumatic episode she had no improvement, and the patient was referred to an orthopedic surgeon in another institution for evaluation. A new MRI was interpreted as being compatible with a soft-tissue sarcoma, and the patient was referred for treatment to our institution. When the patient arrived, she presented with mild pain in her left upper arm, with numbness in the hand when outstretched. The physical examination showed a 15 centimeter, firm, non-tender soft-tissue mass in the left upper arm along the biceps muscle that adhered to the subcutaneous tissue. The motor and sensory functions of the left upper extremity were normal. We performed a wide excisional biopsy and found a wellcircumscribed soft-tissue mass located in the left biceps brachii muscle. The pathology sections showed a highgrade sarcoma with a fine vascular background. After the surgical resection, the patient recovered well and received radiation therapy with no relapses or documented metastases at the time this report was made
Imaging provides the clinician with crucial information in the diagnosis, staging, treatment planning, treatment evaluation, and post-treatment assessment of patients with soft-tissue sarcoma. Thanks to high-contrast tissue resolution and multiplanar imaging capability, MRI remains the gold standard for evaluation of most soft-tissues lesions. However, the sensitivity for diagnosis and grading remains controversial in the literature.
MRI is not able to predict malignancy, and the findings commonly associated with malignant lesions frequently overlap with those seen in benign tumors.4 Furthermore, a significant percentage of malignant lesions may appear deceptively benign with the currently used criteria.9,10 MRI also performs poorly in the histological classification of softtissue tumors.10 This is because MRI images provide only indirect information about tumor histology by showing signal intensities related to some physicochemical properties of the tumor components, and consequently reflect gross morphology of the lesion rather than underlying histology. Finally, the time-dependent changes of the tumors (as a consequence of intratumor necrosis and/or bleeding), makes the differentiation process even more difficult.
Differentiating between malignant and benign softtissue lesions has proven to be a difficult task even with the advantage of MRI. Soft-tissue tumors grow in a centrifugal manner until resistance is met. The barriers in soft tissues consist of major fibrous septa and the origins and insertions of muscles. Growth tends to occur in the plane of least resistance, which in soft-tissue tumors occurs in a longitudinal fashion (i.e., in the compartment of origin). The host responds to tumor growth by creating a reactive fibrovascular tissue that forms a limiting capsule in benign lesions.
Aggressive lesions, however, compress the host reactive tissue into a pseudocapsule containing finger-like or nodular tumoral foci called satellite lesions. In highly aggressive lesions, tumoral foci (skip metastases) are found beyond the reactive zone within the compartment of origin.
As we mentioned, MRI usefulness as a valid predictor of malignancy in soft-tissue lesions is debatable. However there are some individual parameters for predicting malignancy in MRI images: 1) Intensity and homogeneity of the MR signal on different pulse sequences; 2) High-signal intensity on T2-weighted images; and 3) Homogeneity on T1-weighted images. These are sensitive parameters but present with an unacceptably low specificity.
Indeed, high-grade malignant soft-tissue tumors may show low-to-intermediate signal intensity on T2-weighted images because of an increased nucleocytoplasmic index and an altered cellular and interstitial components proportion, both resulting in a decrease of intra- and extra-cellular water.1,2 Hermann et al. reported that changes in homogeneity (from homogeneous on T1- weighted images to heterogeneous on T2-weighted images) and the presence of low-signal intratumoral septations have a sensitivity of 72 and 80 percent and a specificity of 87 and 91 percent, respectively, in predicting malignancy.
Other signs related to malignancy include the presence of tumor necrosis, bone or neurovascular involvement, mean diameter of more than 66 millimeters, and irregular or partially irregular margins.4 Finally, no predominant enhancement pattern is characteristic of benign or malignant lesions. Unfortunately, as deduced from the previous data, none of these parameters is reliable enough to precisely assess the benign or malignant condition of a lesion on MRI images. MRI images of acute hematomas show low-to-intermediate signal intensity on T1, and low signal on T2. These same findings are seen in desmoids and other fibromatoses, pigmented villonodular synovitis, fibrolipohamartomas, giant cell tumors of the tendon sheath, xanthomas, high-flow arteriovenous malformations, mineralized masses, scar tissue, amyloidosis, granuloma annulare and high-grade sarcomas. Intratumoral hemorrhage is a rare finding that can be observed in benign and malignant lesions, and is difficult to differentiate from non-tumoral soft-tissue hematoma.
Moulton et al.11 evaluated 23 benign and 5 malignant tumors with hemorrhage in a total of 225 masses. Hemorrhage was diagnosed on the basis of high signal on T1-weighted images, coupled with low or high signal on T2-weighted images, provided the tissue was not isointense to fat in all sequences. A lowsignal hemosiderin rim was interpreted as evidence of prior hemorrhage. In Table 1 we show the MRI image characteristics of some of the more common soft-tissue lesions and hematomas.
There are three reports in the literature of high-grade sarcomas mimicking hematomas in the extremities. Ogose et al.12 reported an extra-skeletal Ewing sarcoma mimicking a traumatic hematoma in a 16-year-old boy with a history of recurrent hematoma in the thigh.
These lesions were characterized by rapid growth. Interestingly, the cytology of percutaneous aspiration was negative for malignancy in five of the six patients, and the final diagnosis was only made after an open biopsy several weeks later. Finally, Engel et al.,6 reported on a young man who received trauma to his thigh that was initially diagnosed as an organizing hematoma of the adductor compartment.
At surgery, evidence of a tumor was found that was histologically identified as a synovial sarcoma. In their study8, Imaizumi et al. retrospectively reviewed the history and imaging studies and concluded that MRI was a reliable diagnostic tool for the differentiation between hematoma and sarcoma.
However, as presented in this report, the MRI images can be very similar in both pathologies, and high-grade soft-tissue sarcoma cases presenting after some degree of trauma could easily be mistaken initially as hematomas related to that recent injury.
We conclude that intramuscular hematomas following trauma should be approached with a high degree of clinical suspicion. MRI analysis can be used as an important diagnostic tool, but the results must be seen in the context of the clinical history. MRI is not sensitive or specific enough to rule out malignancy. The diagnosis of a myxoid sarcoma made with a biopsy.
- Berquist TH, Ehman RL, King BF, Hodgman CG, Ilstrup DM. Value of MR imaging in differentiating benign from malignant soft-tissue masses: study of 95 lesions. AJR Am J Roentgenol 1990; 155(6): 12515.
- De Schepper A, Grading and characterization of soft tissue tumors. Imaging of soft tissue tumors, ed. De Schepper A, (1997), Berlin Heidelberg New York: Springer. 127-139.
- De Schepper A, De Beuckeleer L. Imaging of soft tissue tumors in the pediatric patient. Semin Musculoskeletal Radiol 1999; 3: 59-79.
- De Schepper AM, De Beuckeleer L, Vandevenne J, Somville J. Magnetic resonance imaging of soft tissue tumors. Eur. Radiol 2000; 10: 213-222.
- Eilber FC, Rosen G, Nelson SD, Selch M, Dorey F, Eckardt J, Eilber FR. High-grade extremity soft tissue sarcomas: factors predictive of local. Annals of surgery 2003; 237(2): p. 218.
- Engel C, Kelm J, Olinger A. Blunt trauma in soccer. The initial manifestation of synovial sarcoma. Zentralbl Chir. 2001; 126(1):68-71.
- Hermann G, Abdelwahab I, Miller T, Klein M, Lewis M. Tumour and tumour-like conditions of the soft tissue: magnetic resonance imaging features differentiating benign from malignant masses. Br J Radiol 1992; 65: 14-20.
- Imaizumi S, Morita T, Ogose A, Hotta T, Kobayashi H, Ito T, Hirata Y. Soft tissue sarcoma mimicking chronic hematoma: value of magnetic resonance imaging in differential diagnosis. J Orthop Sci. 2002; 7(1): 33-7.
- Kransdorf M. Benign soft tissue tumors in a large referral population: distribution of specific diagnoses by age, sex and location. Am J Roentgenol 1995; 164: 395-402.
- Kransdorf M. Malignant soft tissue tumors in a large referral population distribution of specific diagnoses by age, sex and location. Am J Roentgenol, 1995; 164:129-134.
11 Moulton JS, Blebea JS, Dunco DM, Braley SE, Bisset GS III, Emery KH. MR imaging of soft-tissue masses: diagnostic efficacy
Fig 1: Subcutaneous sarcoma in T1 saggital sequence
Fig 2 & 3: Subcutaneous sarcoma in T1 axial sequence
Fig 4: Subcutaneous sarcoma in Saggital STIR sequence with minimal muscle invasion.