Imaging Pearls ❯ Musculoskeletal ❯ Soft Tissue and Muscle Tumors
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- “Integrating salient imaging findings with clinical history is crucial when approaching the diagnosis of subcutaneous soft-tissue masses. The diagnosis of endometriosis should be entertained when soft-tissue masses are seen in the distribution of a ce- sarean section scar in a woman of reproductive age. Pain, particularly with a cyclic pattern, is highly suggestive of endometriosis.”
Subcutaneous Abdominal Wall Masses: Radiological Reasoning
Stein L et al.
AJR 2012; 198:W146–W151 - Abdominal Wall Masses: Differential Dx
- hematoma
- injection granulomas
- endometriosis
- abscess
- desmoid tumor
- metastatic disease
- lymphoma - “Desmoid tumors arise from connective tissue in fascia, aponeuroses, and muscle and constitute less than 3% of all soft-tissue tumors. They do not metastasize but have a high tendency to recur after resection and may result in significant local morbidity because of their infiltrative growth.”
Subcutaneous Abdominal Wall Masses: Radiological Reasoning
Stein L et al.
AJR 2012; 198:W146–W151 - "Abdominal wall desmoids typically occur during gestation or in the first year after pregnancy and can arise in the intact abdominal wall or in a cesarean section scar. Other known associations for the occurrence of desmoid tumors include trauma and surgery, familial adenomatous polyposis or Gardner syndrome in the case of mesenteric lesion, and estrogen therapy.”
Subcutaneous Abdominal Wall Masses: Radiological Reasoning
Stein L et al.
AJR 2012; 198:W146–W151 - "Subcutaneous lymphomas may be classified as primary (rare) or secondary. They can be further subclassified as B cell, T cell, histiocytic, and other. When lymphoma manifests as a subcutaneous mass, imaging features are often nonspecific. The search for ancillary imaging findings, including adjacent osseous abnormalities or lymphadenopathy, often help to support the diagnosis of lymphoma.”
Subcutaneous Abdominal Wall Masses: Radiological Reasoning
Stein L et al.
AJR 2012; 198:W146–W151 - "The CT appearance of endometriosis is nonspecific. Abdominal wall endometriosis usually has the appearance of a solid ill-defined mass with internal density similar to that of muscle and mild enhancement after IV contrast administration. With intrapelvic endometriosis, a cystic mass is often seen. CT may be helpful for delineating the extent of abdominal wall endometriosis for surgical planning, determining fascial involvement, and excluding other diagnostic considerations.”
Subcutaneous Abdominal Wall Masses: Radiological Reasoning
Stein L et al.
AJR 2012; 198:W146–W151 - “Abdominal wall endometriosis typically occurs at the site of prior surgery or trauma in the abdominal wall. It can occur independently of the presence of endometriosis elsewhere in the body and is thought to occur secondary to direct implantation of endometrial cells into the abdominal wall during surgery. This phenomenon has an incidence of between 0.3% and 15% after cesarean section.”
Imaging Spectrum of Endometriosis (Endometriomas to Deep Infiltrative Endometriosis)
Nicole Hindman, Wendaline VanBuren
Radiol Clin N Am 58 (2020) 275–289
- ‘Schwannomas are typically slow growing, encapsulated benign neoplasms. Visceral schwannomas are rare, and preoperative diagnosis is challenging, as they are often confused with other neoplasms even with advanced imaging studies. Surgical excision is usually needed to establish a definitive diagnosis, as pathology is the "gold standard." We review the imaging findings of abdominal schwannomas focusing on pancreatic, gastrointestinal, and retroperitoneal/adrenal schwannomas with pathology correlation. We conclude that schwannoma should be included in the broad differential diagnosis of an abdominal mass and that when it is unnecessary radical resection can be avoided.”
Abdominal schwannomas: review of imaging findings and pathology. Lee NJ1, Hruban RH2, Fishman EK3. Abdom Radiol (NY). 2017 Jul;42(7):1864-1870 - “On computed tomography (CT) or magnetic resonance imaging (MRI), schwannomas in various anatomic locations are typically a well-demarcated round or oval masses. Calcification and cystic changes may be seen in larger tumors. After contrast enhancement, homogeneous to heterogeneous contrast enhancement may be seen due to variable degree of internal cystic and hemorrhagic changes. Most schwannomas appear as inhomogeneous low-density masses on CT scan images, isointense with muscle on T1-weighted images, and high intensity on T2-weighted images on MRI.”
Abdominal schwannomas: review of imaging findings and pathology. Lee NJ, Hruban RH, Fishman EK Abdom Radiol (NY). 2017 Jul;42(7):1864-1870 - “Abdominal Schwannoma is rare and preoperative diagnosis is challenging because of the lack of definitive non-histological diagnostic modalities, as imaging findings are not specific even with developed advanced imaging techniques. Surgical excision is required for treatment and to provide a definitive diagnosis made by histological and immunohistochemical evaluations. Understanding the image findings of abdominal schwannomas will help with considering schwannoma in differential diagnosis appropriately to guide treatment plan and to avoid an unnecessary radical resection.”
Abdominal schwannomas: review of imaging findings and pathology. Lee NJ, Hruban RH, Fishman EK Abdom Radiol (NY). 2017 Jul;42(7):1864-1870 - “Bone is normally resistant to infection, but trauma, bacteremia, surgery, or foreign bodies may disrupt and lead to the onset of osteomyelitis. It is a difficult-to-treat condition characterized by progressive inflammatory destruction and new apposition of bone.1 It is most commonly caused by pyogenic bacteria and mycobacteria. Its manifestations are heterogeneous, depending on the age of the patient, specific causative microorganism, anatomic area of involvement, segment of affected bone, route of contamination, systemic and local host factors, as well as the presence of underlying comorbidities.”
Radiographic Imaging in Osteomyelitis: The Role of Plain Radiography, Computed Tomography, Ultrasonography, Magnetic Resonance Imaging, and Scintigraphy Carlos Pineda et al. Semin Plast Surg. 2009 May;23(2): 80–89. - “The major role of this technique in osteomyelitis is the detection of sequestra in cases of chronic osteomyelitis, as these pieces of necrotic bone can be masked by the surrounding osseous abnormalities on conventional radiography. The presence of pieces of sequestered bone suggests activity of the infectious process, and their detection is helpful to guide the therapeutic options. CT is superior to MRI for the detection of sequestra, cloacas, involucra, or intraosseous gas and can help in the guidance of needle biopsies and joint aspiration; furthermore, it is also valuable in cases of vertebral osteomyelitis..”
Radiographic Imaging in Osteomyelitis: The Role of Plain Radiography, Computed Tomography, Ultrasonography, Magnetic Resonance Imaging, and Scintigraphy Carlos Pineda et al. Semin Plast Surg. 2009 May;23(2): 80–89. - “CT provides excellent multiplanar reconstructions of the axial images allowing delineation of even the most subtle osseous changes. In chronic osteomyelitis, CT demonstrates abnormal thickening of the affected cortical bone, with sclerotic changes, encroachment of the medullary cavity, and chronic draining sinus. Although CT may show these changes earlier than do plain radiographs, CT is less desirable than MRI because of decreased soft tissue contrast as well as exposure to ionizing radiation.”
Radiographic Imaging in Osteomyelitis: The Role of Plain Radiography, Computed Tomography, Ultrasonography, Magnetic Resonance Imaging, and Scintigraphy Carlos Pineda et al. Semin Plast Surg. 2009 May;23(2): 80–89. - “Primary retroperitoneal sarcomas are both rare and diverse. Within this subset of diagnoses, the three most prevalent entities are liposarcoma, leiomyosarcoma, and malignant brous histiocytoma. Among these three, liposarcoma is the most common, as it represents 35% of all malignant retroperitoneal soft-tissue tumors in adult patients.”
Fat-containing Lesions of the Retroperito- neum: Radiologic-Pathologic Correlation Craig WD et al. RadioGraphics 2009; 29:261–290 - “Most patients with liposarcoma are 50–70 years old, and the tumor has no gender predilection. Patients present with symptoms that relate to tumor location, size, and impingement on adjacent structures. If the tumor can be fully resected, the prognosis for a patient with well-differentiated liposarcoma is good. However, retroperitoneal liposarcomas tend to grow to large proportions before coming to clinical attention; thus, complete surgical resection is often not possible and recurrence rates approach 100%.”
Fat-containing Lesions of the Retroperitoneum: Radiologic-Pathologic Correlation Craig WD et al. RadioGraphics 2009; 29:261–290 - “At CT, the lesions demonstrate fat attenuation. In follow-up CT evaluations for recurrent disease, the tumor reportedly has slightly higher attenuation compared with that of normal retroperitoneal fat .”
Fat-containing Lesions of the Retroperitoneum: Radiologic-Pathologic Correlation Craig WD et al. RadioGraphics 2009; 29:261–290
- “Lesions predominantly composed of fibrous tissue are usually of intermediate density similar to that of muscle. Benign fibrous masses include nodular fasciitis, fibromas, and fibromatoses, the last of which can recur and be locally aggressive. Uncommon in the extremities, solitary fibrous tumors are a type of spindle cell neoplasm originally described in the pleura but now recognized to be anatomically ubiquitous and of uncertain malignant potential; their CT appearance is typically that of a well-defined mass nearly isodense to muscle.”
Soft-Tissue Masses and Masslike Conditions: What Does CT Add to Diagnosis and Management? Ty K. Subhawong Elliot K. Fishman,Jennifer E. Swart,John A. Carrino,Samer Attar, Laura M. Fayad AJR Am J Roentgenol. 2010 Jun; 194(6): 1559–1567 - “CT angiography may aid in the characterization of soft-tissue masses by revealing arterial or venous lesion vascularity, which is characteristic of certain tumors or vascular malformations. CT angiography is especially useful for preoperative planning by depicting vascular structures with a high degree of spatial resolution in multiple planes and in 3D reconstructions.”
Soft-Tissue Masses and Masslike Conditions: What Does CT Add to Diagnosis and Management? Ty K. Subhawong Elliot K. Fishman,Jennifer E. Swart,John A. Carrino,Samer Attar, Laura M. Fayad AJR Am J Roentgenol. 2010 Jun; 194(6): 1559–1567 - “The primary role of CT in the evaluation of soft-tissue masses is adjunctive to that of MRI for the characterization of the masses. With CT, subtle areas of matrix mineralization may be detected that are diagnostic for a specific entity when minute areas of ossification or calcification are undetectable by MRI or radiography. Lesion density can suggest a histologic diagnosis, and careful evaluation of the adjacent bone often reveals clues regarding the potential for aggressive behavior.”
Soft-Tissue Masses and Masslike Conditions: What Does CT Add to Diagnosis and Management? Ty K. Subhawong Elliot K. Fishman,Jennifer E. Swart,John A. Carrino,Samer Attar, Laura M. Fayad AJR Am J Roentgenol. 2010 Jun; 194(6): 1559–1567
- The most frequent findings were the following: ribs erosion (19.8%), pectus excavatum (12.0%), kyphoscoliosis (3.5%) and posterior mediastinal masses (7.1%). Such results suggest that posterior mediastinal masses (neurofibroma and meningocele) should be included as a diagnostic criterion of type 1 neurofibromatosis, in conjunction with dysplasia of the sphenoid wing, pseudoarthrosis and thinning of long bone cortex, as defined by the National Institutes of Health.
Type 1 neurofibromatosis: radiological findings of the chest* Marcos Pontes Muniz et al. Radiol Bras vol.43 no.3 São Paulo May/June 2010 - Neurofibromatosis (NF) is an autosomal dominant disease that was first described by Friedrich von Recklinghausen in 1882. Several types of NF have been described, and type 1 (NF1), also denominated peripheral or classic NF, is the most common, occurring in 1:3,000 individuals. One of the main characteristics of this disease is systemic and progressive involvement, with impaired neurological functions and physical deformity.
The diagnostic criteria for NF1 were defined by the National Institutes of Health (NIH) in 1987 and updated three years later(5). Main clinical presentations of NF1 include café-au-lait spots, cutaneous neurofibromas, ephelides or freckling in axillary and/or inguinal regions, plexiform neurofibromas and Lisch nodules
Type 1 neurofibromatosis: radiological findings of the chest* Marcos Pontes Muniz et al. Radiol Bras vol.43 no.3 São Paulo May/June 2010 - “The commonest alterations include scoliosis, kyphoscoliosis, erosion of the posterior wall of vertebral bodies, erosion of the anterior wall of vertebral bodies, widening of intervertebral foramina, growth disorders, pseudoarthrosis, thinning of long bone cortices, bone cystic lesions, costal arch erosion, thinning of pedicles, sphenoid wing dysplasia, cranial osteolytic lesions, facial/mandibular deformities, subperiosteal bone proliferation, bone compression due to soft-tissue tumors (neurofibromas, dura mater dysplasias, intrathoracic meningocele)”
Type 1 neurofibromatosis: radiological findings of the chest* Marcos Pontes Muniz et al. Radiol Bras vol.43 no.3 São Paulo May/June 2010 - “Among the alterations found in the analysis of chest radiographs, costal arch irregularities were the most common ones (19.1%). This abnormality may occur due to a primary dysplastic defect in bone formation or by erosion of an intercostal neurofibroma(8,10,14). A "twisted-ribbon" appearance of the ribs is frequently reported”
Type 1 neurofibromatosis: radiological findings of the chest* Marcos Pontes Muniz et al. Radiol Bras vol.43 no.3 São Paulo May/June 2010 - “About 80% of patients presenting with intrathoracic meningoceles have NF1(25,26). Two or more skin neurofibromas or one plexiform neurofibroma are diagnostic criteria of NF1 as defined by the NIH). Thus, the presence of neurofibromas in the paravertebral regions should be considered as of equal value in the diagnosis of NF1. No information on the incidence of posterior mediastinal masses in the general population was found in the literature.”
Type 1 neurofibromatosis: radiological findings of the chest* Marcos Pontes Muniz et al. Radiol Bras vol.43 no.3 São Paulo May/June 2010
- “ Image reviewers were relatively poor at even side-by-side matching of patient photographs with 3D surface-reconstructed images. This finding suggests that successful identification of patients using surface-rendered faces may be a relatively difficult task for observers.”
Implications of surface-rendered facial CT images in patient privacy.
Chen JJ et al.
AJR. 2014 Jun;202(6):1267-71 - “Three-dimensional and multiplanar reconstruction of CT images has become routine in diagnostic imaging. The technology also facilitates surface reconstruction, in which facial features and, as a result, patient identity may be recognized, leading to risk of violations of patient privacy rights. The purpose of this study was to assess whether volunteer viewers can recognize faces on 3D reconstructed images as specific patients.”
Implications of surface-rendered facial CT images in patient privacy.
Chen JJ et al.
AJR. 2014 Jun;202(6):1267-71
- “Metastases to skeletal muscle have been reported from pancreatic, renal, colonic , pulmonary, gastric, and ovarian primary malignancies.”
Helical CT of Skeletal Muscle Metastases from Primary Carcinomas
Pretorius ES, Fishman EK
AJR 2000;174:401–404 - “Several factors have been postulated to contribute to the resistance of skeletal muscle to metastatic disease. These factors include muscle motion and mechanical tumor destruction, inhospitable muscle pH, and the muscle’s ability to remove tumor-produced lactic acid that induces tumor neovascularity in other tissues.”
Helical CT of Skeletal Muscle Metastases from Primary Carcinomas
Pretorius ES, Fishman EK
AJR 2000;174:401–404 - “In conclusion, metastases to skeletal muscle are features of advanced-stage neoplasms and may be more common than previously suspected. They may be incidental findings on CT of the chest or abdomen, for most of the lesions in our series were neither painful nor palpable. The most common appearance of the lesions on contrast-enhanced helical CT is that of a rim-enhancing mass with central hypoattenuation.”
Helical CT of Skeletal Muscle Metastases from Primary Carcinomas
Pretorius ES, Fishman EK
AJR 2000;174:401–404 - “ Skeletal muscle metastases are not rare. They may be more apparent at fused positron emission tomography and computed tomography than at other staging examinations, particularly contrast-enhanced CT scanning. Radiologists need to be alert to their presence when interpreting staging examinations in cancer patients.”
Skeletal muscle metastases: a three-part study of a not-so-rare entity
Haygood TM et al.
Skeletal Radiol. 2012 Aug;41(8):899-909. - “We found 264 cases of skeletal muscle metastases in 151 articles. Mean age was 57.8 years with 67% men. At our hospital we studied 70 cases. Mean patient age was 55.7 years with 63% men. The most common source was lung cancer, and the most common site of involvement was the muscles of the trunk.”
Skeletal muscle metastases: a three-part study of a not-so-rare entity
Haygood TM et al.
Skeletal Radiol. 2012 Aug;41(8):899-909.
- “ The skin and SQ tissues are by definition on the periphery of CT images and may often be overlooked by the interpreting radiologist. These findings may also be only partially included in the field of view, further complicating identification and interpretation.”
CT of the skin and subcutaneous tissues
Katz DS et al.
Emerg Radiol (2013):20;57-68 - Skin and Soft Tissue Pathology: CT Findings
- Trauma (laceration, bleed)
- Infection (abscess)
- Foreign body (silicon injections)
- Hematoma
- Calcifications
- Soft tissue tumors (melanoma, lymphoma)
- “Renal cell carcinoma (RCC) is a tumor known for its unusual presentations and high rate of metastasis. Metastasis to lung, liver, bone and brain are common, but to skeletal muscle(SM) is very rare. Because only 11% of the RCC metastases to SM present after 10 years of initial presentation, there is no general consensus for its annual surveillance.”
A large thigh mass: a blood clot or a rare skeletal muscle metastasis from renal cell carcinoma
Lohiya V et al.
Springerplus 2013 Aug 23;2:399 - Metastases to Muscle
- Renal cell carcinoma
- Lung cancer
- Melanoma
- Lymphoma
- Breast cancer - “SMM manifested on PET/CT as focal hypermetabolic intramuscular areas with different SUV. There were no significant differences between SUV or size of the identified SMM in esophageal cancer, renal cell carcinoma, and lung cancer.”
PET/CT imaging of skeletal muscle metastases.
Surov A et al.
Acta Radiol. 2013 Jul 24. [Epub ahead of print]
- “ Abdominal CSF pseudocysts (APC) are a relatively uncommon complication of VP shunts, with a reported occurrence of 0.7% – 4.5% . The complete lack of mesothelial lining classifies them as pseudocysts . Although pediatric patients may often present with headaches, nausea and vomiting, adult patients with APC typically present with abdominal symptoms rather than neurological complaints. Such symptoms may include distension, pain, or focal mass. In addition, these patients may present with abdominal complaints years after their shunt procedures.”
Abdominal cerebrospinal fluid pseudocyst mimicking full-term pregnancy
Wang BH, Hasadsri L, Wang H
J Surg Case Rep (2012) Issue 7, Pg 6 - “VP shunt placement may result in a number of potential abdominal complications, including infection, bowel obstruction, volvulus, ileus, and perforation from direct catheter erosion into the gallbladder or bowel. Abdominal peritoneal pseudocysts (APC) are a relatively uncommon complication of VP shunts, with occurring in less than 5% of cases according to previously published reports.”
Abdominal cerebrospinal fluid pseudocyst mimicking full-term pregnancy
Wang BH, Hasadsri L, Wang H
J Surg Case Rep (2012) Issue 7, Pg 6
- “Cutaneous T-cell lymphomas are rare, distinct forms of non-Hodgkin's lymphomas. Of which, mycosis fungoides (MF) and Sézary syndrome (SS) are two of the most common forms.”
A practical approach to accurate classification and staging of mycosis fungoides and Sézary syndrome.
Thomas BR, Whitaker S
Skin Therapy Lett 2012 Dec; 17(10):5-9 - “Approximately one-fourth of cutaneous lymphomas are B-cell derived and are generally classified into three distinct subgroups: primary cutaneous follicle-center lymphoma (PCFCL), primary cutaneous marginal zone lymphoma (PCMZL), and primary cutaneous diffuse large B-cell lymphoma, leg type (PCLBCL, LT).”
Cutaneous B-cell lymphomas: 2013 update on diagnosis, risk-stratification, and management
Wilcox RA
Am J Hematol 2013 Jan;8891);73-76 - “The term extranodal disease refers to lymphomatous infiltration of anatomic sites other than the lymph nodes. Almost any organ can be affected by lymphoma, with the most common extranodal sites of involvement being the stomach, spleen, Waldeyer ring, central nervous system, lung, bone, and skin. The prevalence of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease has increased in the past decade. The imaging characteristics of extranodal involvement can be subtle or absent at conventional computed tomography (CT). Imaging of tumor metabolism with 2-[fluorine-18]fluoro-2-deoxy-d-glucose (FDG) positron emission tomography (PET) has facilitated the identification of affected extranodal sites, even when CT has demonstrated no lesions. More recently, hybrid PET/CT has become the standard imaging modality for initial staging, follow-up, and treatment response assessment in patients with lymphoma and has proved superior to CT in these settings.”
FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease
RadioGraphics 2010 Jan;30(1):269-91 - “The term extranodal lymphoma has been used to describe this uncommon form of lymphoid malignancy, in which there is neoplastic proliferation at sites other than the expected native lymph nodes or lymphoid tissues. Distribution among the non-lymphoid tissues is uneven, with greater predilection for some organs than for others, and includes the gastrointestinal tract, head and neck (Waldeyer ring), orbit, central nervous system (CNS), lung, bone, and skin. The prevalence and distribution among organs vary significantly depending on histologic type and disease stage.”
FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease
RadioGraphics 2010 Jan;30(1):269-91 - “Cutaneous lymphomas may manifest either as primary tumors or as secondary to disseminated disease. Primary cutaneous lymphoma is the second most prominent group of NHLs (67), whereas primary or secondary skin involvement is very rare in patients with Hodgkin disease. Almost 65% of primary cutaneous lymphomas are T-cell lymphomas (Fig 13), with the remainder being B-cell lymphomas. About 25% of primary cutaneous lymphomas demonstrate extracutaneous involvement at the time of diagnosis. The presence of extracutaneous disease in primary cutaneous lymphoma is important in treatment planning and in predicting prognosis at initial staging and posttherapy restaging. Cutaneous lymphoma is a heterogeneous group of diseases.”
FDG PET/CT of extranodal involvement in non-Hodgkin lymphoma and Hodgkin disease
RadioGraphics 2010 Jan;30(1):269-91