Introduction:
Isolated bone lesions are frequently observed in radiological practice every day. Due to this, it is critical to distinguish between lesions that can be aggressive and malignant (cancerous) and that call for treatment and those that are benign (non-cancerous), often harmless, and associated with reactive processes but have no medical significance.
What Is Do Not Touch Lesion in Radiology?
When a lesion exhibits conventional radiographic characteristics and can be diagnosed without necessitating a biopsy, it is referred to as a "do not touch lesion." Recent developments in imaging methods help to classify a large number of incidental lesions as "do not touch lesions” based solely on how they appear on imaging and, occasionally, through additional blood investigations to help refrain from the need for a biopsy. Sometimes, these lesions are mistaken as neoplastic tumors, raising concerns and prompting needless medical interventions. When these lesions are correctly identified and given a particular diagnosis, the morbidity and treatment expenses related to them are reduced.
What Are the Types of Do Not Touch Lesion?
Three categories can be used to group lesions that should not be touched:
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Post-traumatic lesions.
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Normal variants.
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Real but benign lesions.
What Are Some Examples of Lesions That Are Real but Benign?
Some of the lesions that are included in real but benign lesions are as follows:
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Cortical Desmoids: Cortical desmoids are benign (non-cancerous), self-limiting entities that are frequently discovered by accident. They are sometimes referred to as cortical avulsive injuries, distal femoral cortical defects, or irregularities. This lesion generally displays a radiolucent cortical abnormality in the shape of a saucer at the point where the adductor magnus tendon attaches to the posteromedial portion of the distal femoral metaphysis. There is no exterior boundary to the lesion.
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Subchondral Cysts: A fluid-filled sac that develops in the bone under the cartilage of a joint, like the hip, knee, or shoulder, is called a subchondral cyst. Another name for it is a bone cyst. Subchondral denotes a location underneath the cartilage. Those with osteoarthritis may acquire these cysts. In X-rays, these lesions appear as circular, radiolucent lesions with clearly defined margins.
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Costochondritis (Tietze's Syndrome): The cartilage where the ribs connect to the breastbone is inflamed painfully in cases of Tietze syndrome. The damaged costochondral joints develop pain, soreness, and swelling due to the Tietze syndrome. It mostly impacts the second or third ribs, which are closer to the ribcage's shoulders. A magnetic resonance imaging (MRI) scan reveals enlargement of the cartilage.
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Small Bone Islands: Formerly known as enostoses, bone islands are often benign sclerotic bone lesions that are typically discovered by chance. They are referred to as osteomas when they develop in the head. Bone islands belong to the category of skeletal lesions that should not be touched.
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Fibrous Dysplasia: A benign (noncancerous) bone disorder called fibrous dysplasia causes aberrant fibrous tissue to grow instead of healthy bone. Over time, the growth and expansion of these fibrous tissue patches can weaken the bone, making it more prone to fractures or deformities.
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Non-ossifying Fibroma: Up to 40 percent of children have non-ossifying fibromas, which are the most prevalent benign bone tumors. They develop on long bones, particularly the legs, and are composed of fibrous tissue. They do not proliferate or become malignant. Non-ossifying fibromas spontaneously disappear as the child reaches adulthood.
What Are the Lesions Included in Post-traumatic Lesions?
Leions included in post-traumatic lesions are as follows:
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Myositis Ossificans: It is a benign disorder where a bone-like structure develops inside the muscles or other soft tissues. It usually impacts larger muscles in the arms and legs. It is the most common type of heterotropic ossification. When this develops, one can feel a painful lump.
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Discogenic Vertebral Sclerosis: It is a type of “do not touch lesion”. This should not be mistaken for infection in disc space and cancerous lesions. It could result in unwanted biopsy. It is characterized by persistent pain in the lower back. It is more prevalent in middle-aged women.
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Pseudodislocation of the Shoulder: A hidden fracture with glenohumeral joint distension from hemarthrosis (bleeding into the joint cavity) results in the inferior dislocation of the humeral head, which leads to pseudo-dislocation of the shoulder. This could be confused with a dislocated shoulder joint. Sometimes, physicians may try to relocate the humeral head, although this is painful and ineffective. Thus, one of the bones, "do not touch lesions” is a pseudo dislocation of the humerus.
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Avulsion Injuries: The ligament, tendon, or muscle attachment site can be ripped away from the bone in an avulsion injury or fracture, typically removing a piece of cortical bone with it. Because avulsion fractures entail strong tensile pressures, they are frequently overlooked. These take place at a variety of locations. It is critical to understand them because subacute and chronic injuries can seem aggressive. There are three types of avulsion fractures: acute, subacute, and chronic. A clear traumatic occurrence frequently precedes acute avulsion fractures. Subacute and chronic avulsion injuries can result from frequent use injuries, or they might be caused by the postponed manifestation of an acute injury. Usually, the avulsed bone fragment migrates in the course of the ligament, tendon, or joint capsule that is linked to it.
What Are the Lesions Included in Normal Variants?
Normal variants are as follows:
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Pseudocyst of the Humerus: A lucent lesion on radiography, the pseudocyst of the humerus is a typical morphological variance caused by excessive cancellous bone in the region of the humerus's greater tuberosity. Due to hyperemia (an excessive amount of blood in a particular body area's blood vessels) and inactivity brought on by shoulder issues, this area of lucency wrongly undergoes biopsy because it seems more lucent and mimics a lytic lesion.
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Dorsal Defects of the Patella: Dorsal defects of the patella are typical patellar growth-related aberrations and benign lesions with no known cause. Sometimes, these lesions are misdiagnosed as an actual disease, such as osteochondritis dissecans (a disorder of the joint brought on by inadequate blood supply to the bone beneath the cartilage) or an infection focus.
Conclusion:
Radiologists and radiology residents must possess knowledge about "do not touch" lesions and how they manifest differently using different imaging modalities. As a result, they can proficiently participate in these patients' diagnosis and monitoring, helping to minimize the need for needless intrusive treatments, lower the mortality rate, and make the most use of available medical resources.
