 Hello everyone, I'm Dr. Solan Saran and I'm working as assistant professor in the department of creative diagnosis in Trishikesh and I have a special interest in musculoskeletal imaging. So I present series of video tutorials which deals with radiological diagnosis of bone tumours. So starting with the first in the series is this, how to approach a bone tumour. So bone tumours can be classified into three types, first is the primary which can again be divided into venine or malignant and second is the secondary or metastatic which is actually the most common malignant bone tumour. And third is the tumour like process which includes multiple lesions which are actually not tumour but they mimic or behave like a tumour. So we require multiple information before we make any diagnosis of bone tumour. The first and foremost is the age of the patient. So age of the patient is very important because there are certain groups of tumour which are seen in younger population and there are certain groups of tumour which are seen in elderly age group. So age is the most important factor for meeting a diagnosis of bone tumour. Then we need to know whether the lesion is single or multiple. So mostly the tumours are single, however we can see multiple lesions like in this case of multiple osteoconromas. So multiple lesions can be seen in cases of fibrosis plasia, osteoconroma and congroma or they can be seen in malignant entities like multiple myeloma or metastasis. So multiplicity can be seen in both benign and malignant entities. Then location in the skeleton is very important because every tumour has three or four favourite locations within the skeleton. So there are certain group of tumours which are more predominantly seen in the axial skeleton and there are certain tumours which are more commonly seen in the appendicular skeleton. So we need to know the favourite location of certain tumours. Then site of long bone involvement. So within a long bone tumour can be localised to epiphysis, metaphysis or diaphysis and we can also classify this location based on the age group. So we need to know whether the pysis is open or it is closed. So we need to know the site of certain tumours within the long bone for meeting the accurate diagnosis of its entity. Then comes the pattern of growth and bone destruction. So bone tumour can have a geographic pattern of bone destruction or moth-ethan and permeative pattern of bone destruction. So geographic pattern of bone destruction points towards benign entity whereas malignant lesions generally have moth-ethan or permeative pattern of bone destruction. So let's see this case. This is the case of osteosarcoma and we can see there is permeative pattern of bone destruction and this lesion is having a wide zone of transition. We cannot actually draw a line that distinguish defeats bone from the healthy bone. So this lesion is having a wide zone of transition and is having a permeative pattern of bone destruction. This is a malignant bone tumour. And this is a case of giant cell tumour which is actually having a geographic pattern of bone destruction and it is having a sharp margin of transition. However, there are certain exceptions to this rule. So multiple myeloma and meds can have a geographic pattern of bone destruction whereas infection which is a benign entity, it can have permeative pattern of bone destruction. Coming to the types of periostal reactions. So there are multiple types of periostal reaction which can be categorized into non-aggressive and aggressive types. So I will deal with the periostal reaction in a separate video but this is the case of benign looking periostal reaction and this is the case of osteosarcoma giving aggressive periostal reaction. Coming to the pattern of matrix mineralization. So matrix can be of Oshir's type like in the case of osteosarcoma or it can be of cartilaginous matrix like in this case of congo sarcoma or scapula where the matrix is looking like a ring or arc pattern or flocculant stripled pattern of mineralization. Finally, the soft tissue involvement. So if there is soft tissue involvement then it points towards aggressive bone tumor. Let's talk about the modalities which we can use for evaluation of the bone tumor starting with the plane radiograph which is the best and the most important radiological investigation that we use for making diagnosis of bone tumor. Second is the computed tomography or CT scan which is indicated only for certain reasons like if the tumor is located in an area which is difficult to evaluate on plane radiograph like if the tumor is located in the sacrum or in the scapula. So we can order computed tomography for this and the CT is also good for seeing the matrix mineralization and cortical destruction. Then MRI. There are four or five indications for which we need MRI. So first is the extent of medullary involvement in a bone. So lesion may look like having a small extent of involvement on plane radiograph but when we order MRI we see there is extensive medullary involvement and there are presence of keplation. MRI is also good for actually the best for evaluation of neuro vascular involvement and we can use contrast in the evaluation of bone tumor. And if the lesion is having extensive enhancement then it indicates viability and we can target the most enhancing area of the tumor for the biopsy. And MRI is actually used for follow-up of the patients who are on chemotherapy. And last is the bone scintigraphy which is ordered for the evaluation of multiple metastatic lesions in the skeleton can also be used for the evaluation of osteoma. So what is periosteal reaction? It is a response of the cortical bone to many possible insults. So that insult can be a tumor, it can be infection, it can be a trauma like stress fracture, it can be arthritis or the cause can be metabolic. So there are multiple causes which can lead to periosteal reaction. So what are the types of periosteal reaction? The periosteal reaction can be categorized into two types, non-aggressive and aggressive. In non-aggressive category we have thin, unilamilar periosteal reaction, thick, solid type of periosteal reaction, a regular type of periosteal reaction or a subcated type of periosteal reaction. Whereas in aggressive category we can have multilamilar, onion skin type of periosteal reaction, hereon ant type of periosteal reaction, sunburst type of periosteal reaction, disorganized type of periosteal reaction and Godman angle type of periosteal reaction. So let's see non-aggressive pattern first. So this is the case of extensive fibrous dysplasia involving right femoral, head, neck and proximal diaphysis. So as we can see there is presence of thin, unilamilar type of periosteal reaction in this benign entity. This is the case of chronic osteomalitis involving distal metaphysis of femur where we can see there is thick solid periosteal reaction here. So this is the case of thick solid periosteal reaction. This is the case of osteofibrous dysplasia involving tibia where we can see presence of subcated type of periosteal reaction. So these were the non-aggressive pattern of periosteal reaction. Now let's see the aggressive category. This is the case of even sarcoma in which we can see multi-layered or onion skin type of periosteal reaction and it is also interrupted in this area. So this is aggressive periosteal reaction. This is the case of osteosarcoma in which we can see both hair on end and sunburst pattern of periosteal reaction. This is again a case of even sarcoma in which we can see a disorganized pattern of periosteal reaction. This is again a case of osteosarcoma in which apart from the hair on end and sunburst pattern of periosteal reaction we can see lifting of periosteum by a tumor tissue which gives an appearance of cod man triangle. So this is the cod man triangle type of periosteum reaction. Apart from tumor we can have multiple other entities which can lead to periosteal reaction. So this is the case of psoriatic arthritis where we can see presence of thick solid periosteal reaction along with erosion. This is a radiograph of infant showing this biological periostitis involving both femurs. This is the case of bronchogenic carcinoma and secondary to the bronchogenic carcinoma is the perineoplastic syndrome. This patient has developed hypertrophic osteoarthopathy representing periosteal reaction in the lower end of femur. This is the case of stress fracture involving metatarsal at the time of recent trauma and after its healing. So here we can see it is organized pattern of periosteal reaction and after healing there is only thin solid periosteal reaction. Periosteal reaction can also be seen in chronic venous stresses leading to disorganized type of periosteal reaction in the lower pibia and fibula. So this was all about periosteal reaction. I hope you have enjoyed the video. Thank you.