Recurrence rate of solid form of tumour is lower than classic form.

Radiographs in osteoid osteoma typically show a round lucency, containing a dense sclerotic central "nidus" (the characteristic lesion in this kind of tumor), surrounded by sclerotic bone. The nidus is seldom larger than 1.5 cm.

The lesion can in most cases be detected on CT scan, bone scans and angiograms. Plain radiographs are not always diagnostic. MRI adds little to the CT findings which are useful for localisation. Radionuclide scanning shows intense uptake which is useful for localisation at surgery using a hand held detector, and for confirmation that the entire lesion has been removed.

When diagnosing osteoblastoma, the preliminary radiologic workup should consist of radiography of the site of the patient's pain. However, computed tomography (CT) is often necessary to support clinical and plain radiographic findings suggestive of osteoblastoma and to better define the margins of the lesion for potential surgery. CT scans are best used for the further characterization of the lesion with regard to the presence of a nidus and matrix mineralization. MRI aids in detection of nonspecific reactive marrow and soft tissue edema, and MRI best defines soft tissue extension, although this finding is not typical of osteoblastoma. Bone scintigraphy (bone scan) demonstrates abnormal radiotracer accumulation at the affected site, substantiating clinical suspicion, but this finding is not specific for osteoblastoma. In many patients, biopsy is necessary for confirmation.

Chondromyxoid fibromas can share characteristics with chondroblastomas with regards to histologic and radiographic findings. However they more commonly originate from the metaphysis, lack calcification and have a different histologic organization pattern. Other differential diagnoses for chondroblastoma consist of giant cell tumors, bone cysts, eosinophilic granulomas, clear cell chondrosarcomas, and enchondromas (this list is not exhaustive).

Following conditions are excluded before diagnosis can be confirmed:

- Unicameral bone cyst

- Giant cell tumor

- Telangiectatic osteosarcoma

- Secondary aneurysmal bone cyst

Chondroid differentiation is a common feature of chondroblastoma. A typical histological appearance consists of a combination of oval mononuclear and multi-nucleated osteoclast-type giant cells. However this is not a prerequisite for diagnosis, as cells with epithelioid characteristics have been observed in lesions of the skull and facial bones. A "chicken-wire" appearance is characteristic of chondroblastoma cells and is the result of dystrophic calcification that may surround individual cells. Although, calcification may not be present and is not a prerequisite for diagnosis. Mitotic figures can be observed in chondroblastoma tissue but are not considered atypical in nature, and therefore, should not be viewed as a sign of a more serious pathology. There is no correlation between mitotic activity and location of the lesion. Furthermore, the presence of atypical cells is rare and is not associated with malignant chondroblastoma. There are no discernible histological differences observed when comparing the aggressive form of chondroblastoma that can cause recurrence or metastases with its less aggressive, benign, counterpart.

The first route of treatment in Osteoblastoma is via medical means. Although necessary, radiation therapy (or chemotherapy) is controversial in the treatment of osteoblastoma. Cases of postirradiation sarcoma have been reported after use of these modalities. However, it is possible that the original histologic diagnosis was incorrect and the initial lesion was an osteosarcoma, since histologic differentiation of these two entities can be very difficult.

The alternative means of treatment consists of surgical therapy. The treatment goal is complete surgical excision of the lesion. The type of excision depends on the location of the tumor.

- For stage 1 and 2 lesions, the recommended treatment is extensive intralesional excision, using a high-speed burr. Extensive intralesional resections ideally consist of removal of gross and microscopic tumor and a margin of normal tissue.

- For stage 3 lesions, wide resection is recommended because of the need to remove all tumor-bearing tissue. Wide excision is defined here as the excision of tumor and a circumferential cuff of normal tissue around the entity. This type of complete excision is usually curative for osteoblastoma.

In most patients, radiographic findings are not diagnostic of osteoblastoma; therefore, further imaging is warranted. CT examination performed with the intravenous administration of contrast agent poses a risk of an allergic reaction to contrast material.

The lengthy duration of an MRI examination and a history of claustrophobia in some patients are limiting the use of MRI. Although osteoblastoma demonstrates increased radiotracer accumulation, its appearance is nonspecific, and differentiating these lesions from those due to other causes involving increased radiotracer accumulation in the bone is difficult. Therefore, bone scans are useful only in conjunction with other radiologic studies and are not best used alone.

On X-ray, giant-cell tumors (GCTs) are lytic/lucent lesions that have an epiphyseal location and grow to the articular surface of the involved bone. Radiologically the tumors may show characteristic 'soap bubble' appearance. They are distinguishable from other bony tumors in that GCTs usually have a nonsclerotic and sharply defined border. About 5% of giant-cell tumors metastasize, usually to a lung, which may be benign metastasis, when the diagnosis of giant-cell tumor is suspected, a chest X-ray or computed tomography may be needed. MRI can be used to assess intramedullary and soft tissue extension.

Pain may be relieved by nonsteroidal anti-inflammatory drugs.

Treatment varies based on the health of the patient. If he/she is otherwise healthy and is not significantly bothered by the pain, the tumor is treated symptomatically with anti-inflammatories. If this therapy fails or the location of the tumor could lead to growth disturbances, scoliosis, or osteoarthritis, surgical or percutaneous ablation may be considered. If surgery is preferred, the individual may be referred to a podiatrist or an orthopedic surgeon to perform the procedure. Post-surgery therapy and strengthening may be needed, depending on the tumor location and health of the individual. While shown to be effective, surgical resection has many potential complications, including difficult intraoperative identification of the tumor, local recurrence from incomplete resection, and resection of weight bearing bone that can necessitate prolonged hospital stays and complicate recovery.

Recently, CT guided radiofrequency ablation has emerged as a less invasive alternative to surgical resection. In this technique, which can be performed under conscious sedation, a RF probe is introduced into the tumor nidus through a cannulated needle under CT guidance and heat is applied locally to destroy tumor cells. Since the procedure was first introduced for the treatment of osteoid osteomas in the early 1990s, it has been shown in numerous studies to be less invasive and expensive, to result in less bone destruction and to have equivalent safety and efficacy to surgical techniques, with 66 to 96% of patients reporting freedom from symptoms. While initial success rates with RFA are high, symptom recurrence after RFA treatment has been reported, with some studies demonstrating a recurrence rate similar to that of surgical treatment. As of July 17, 2014, treatment with incisionless surgery utilizing an MRI to guide high-intensity ultrasound waves to destroy a benign bone tumor in the leg has been demonstrated.

The diagnosis of giant-cell tumors is based on biopsy findings. The key histomorphologic feature is, as the name of the entity suggests, (multinucleated) giant cells with up to a hundred nuclei that have prominent nucleoli. Surrounding mononuclear and small multinucleated cells have nuclei similar to those in the giant cells; this distinguishes the lesion from other osteogenic lesions which commonly have (benign) osteoclast-type giant cells. Soap-bubble appearance is a characteristic feature.

Treatment of bone tumors is highly dependent on the type of tumor.

An osteoma (plural: "osteomata") is a new piece of bone usually growing on another piece of bone, typically the skull. It is a benign tumor.

When the bone tumor grows on other bone it is known as "homoplastic osteoma"; when it grows on other tissue it is called "heteroplastic osteoma".

Osteoma represents the most common benign neoplasm of the nose and paranasal sinuses. The cause of osteomata is uncertain, but commonly accepted theories propose embryologic, traumatic, or infectious causes. Osteomata are also found in Gardner's syndrome. Larger craniofacial osteomata may cause facial pain, headache, and infection due to obstructed nasofrontal ducts. Often, craniofacial osteoma presents itself through ocular signs and symptoms (such as proptosis).

Chemotherapy and radiotherapy are effective in some tumors (such as Ewing's sarcoma) but less so in others (such as chondrosarcoma).

There is a variety of chemotherapy treatment protocols for bone tumors. The protocol with the best reported survival in children and adults is an intra-arterial protocol where tumor response is tracked by serial arteriogram. When tumor response has reached >90% necrosis surgical intervention is planned.

Family physicians and orthopedists rarely see a malignant bone tumor (most bone tumors are benign). The route to osteosarcoma diagnosis usually begins with an X-ray, continues with a combination of scans (CT scan, PET scan, bone scan, MRI) and ends with a surgical biopsy. A characteristic often seen in an X-ray is Codman's triangle, which is basically a subperiosteal lesion formed when the periosteum is raised due to the tumor. Films are suggestive, but bone biopsy is the only definitive method to determine whether a tumor is malignant or benign.

Most times, the early signs of osteosarcoma are caught on X-rays taken during routine dental check-ups. Osteosarcoma frequently develops in the mandible (lower jaw); accordingly, Dentist are trained to look for signs that may suggest osteosarcoma. Even though radiographic findings for this cancer vary greatly, one usually sees a symmetrical widening of the periodontal ligament space. If the dentist has reason to suspects osteosarcoma or another underlying disorder, he or she would refer the patient to an Oral & Maxillofacial surgeon for biopsy. A biopsy of suspected osteosarcoma outside of the facial region should be performed by a qualified orthopedic oncologist. The American Cancer Society states: "Probably in no other cancer is it as important to perform this procedure properly. An improperly performed biopsy may make it difficult to save the affected limb from amputation." It may also metastasise to the lungs, mainly appearing on the chest X-ray as solitary or multiple round nodules most common at the lower regions.

Amputation is the initial treatment, although this alone will not prevent metastasis. Chemotherapy combined with amputation improves the survival time, but most dogs still die within a year. Surgical techniques designed to save the leg (limb-sparing procedures) do not improve the prognosis.

Some current studies indicate osteoclast inhibitors such as alendronate and pamidronate may have beneficial effects on the quality of life by reducing osteolysis, thus reducing the degree of pain, as well as the risk of pathological fractures.

X-rays show lucency of the ossification front in juveniles. In older people, the lesion typically appears as an area of osteosclerotic bone with a radiolucent line between the osteochondral defect and the epiphysis. The visibility of the lesion depends on its location and on the amount of knee flexion used. Harding described the lateral X-ray as a method to identify the site of an OCD lesion.

Magnetic resonance imaging (MRI) is useful for staging OCD lesions, evaluating the integrity of the joint surface, and distinguishing normal variants of bone formation from OCD by showing bone and cartilage edema in the area of the irregularity. MRI provides information regarding features of the articular cartilage and bone under the cartilage, including edema, fractures, fluid interfaces, articular surface integrity, and fragment displacement. A low T1 and high T2 signal at the fragment interface is seen in active lesions. This indicates an unstable lesion or recent microfractures. While MRI and arthroscopy have a close correlation, X-ray films tend to be less inductive of similar MRI results.

Computed tomography (CT) scans and Technetium-99m bone scans are also sometimes used to monitor the progress of treatment. Unlike plain radiographs (X-rays), CT scans and MRI scans can show the exact location and extent of the lesion. Technetium bone scans can detect regional blood flow and the amount of osseous uptake. Both of these seem to be closely correlated to the potential for healing in the fragment.

OCD is classified by the progression of the disease in stages.

There are two main staging classifications used; one is determined by MRI diagnostic imaging while the other is determined arthroscopically. However, both stagings represent the pathological conditions associated with OCD's natural progression.

While the arthroscopic classification of bone and cartilage lesions is considered standard, the Anderson MRI staging is the main form of staging used in this article. Stages I and II are stable lesions. Stages III and IV describe unstable lesions in which a lesion of the cartilage has allowed synovial fluid between the fragment and bone.

Oval, elliptical, or serpentine radiolucency usually greater than 1 cm surrounded by a heavily reactive sclerosis, granulation tissue, and a nidus often less than 1 cm. The margins often appear scalloped on radiograph. Brodie's abscess is best visualized using Computed tomography (CT) scan.

Associated atrophy of soft tissue near the site of infection and shortening of the affected bone. Osteoblastoma may be a classic sign for Brodie's abscess.

Mainly surgical approach has to be taken.

If cavity is small then surgical evacuation & curettage is performed under antibiotic cover.

If cavity is large then after evacuation, packing with cancellous bone chips

Calcinosis cutis (or cutaneous calcification) is a type of calcinosis wherein calcium deposits form in the skin. A variety of factors can result in this condition. The most common source is dystrophic calcification, which occurs in soft tissue as a response to injury. In addition, calcinosis is seen in Limited Cutaneous Systemic Sclerosis, also known as CREST syndrome (the "C" in CREST). In dogs, calcinosis cutis is found in young, large breed dogs and is thought to occur after a traumatic injury.

A sequestrum (plural: sequestra) is a piece of dead bone that has become separated during the process of necrosis from normal or sound bone.

It is a complication (sequela) of osteomyelitis. The pathological process is as follows:

- infection in the bone leads to an increase in intramedullary pressure due to inflammatory exudates

- the periosteum becomes stripped from the osteum, leading to vascular thrombosis

- bone necrosis follows due to lack of blood supply

- sequestra are formed

The sequestra are surrounded by sclerotic bone which is relatively avascular (without a blood supply). Within the bone itself, the haversian canals become blocked with scar tissue, and the bone becomes surrounded by thickened periosteum.

Due to the avascular nature of this bone, antibiotics which travel to sites of infection via the bloodstream poorly penetrate these tissues, hence the difficulty in treating chronic osteomyelitis.

At the same time as this, new bone is forming (known as involucrum). Openings in this involucrum allow debris and exudates (including pus) to pass from the sequestrum via sinus tracts to the skin.

Rarely, a sequestrum may turn out to be an osteoid osteoma, a rare tumor of the bone.

As the causes of local gigantism are varied, treatment depends on the particular condition. Treatment may range from antibiotics and other medical therapy, to surgery in order to correct the anatomical anomaly.

Local gigantism or localised gigantism is a condition in which a certain part of the body acquires larger than normal size due to excessive growth of the anatomical structures or abnormal accumulation of substances. It is more common in fingers and toes, where it is termed macrodactyly. However, sometimes an entire limb may be enlarged.

Calcinosis cutis may be divided into the following types:

- Dystrophic calcinosis cutis

- Metastatic calcinosis cutis

- Iatrogenic calcinosis cutis

- Traumatic calcinosis cutis

- Idiopathic calcinosis cutis

- Idiopathic scrotal calcinosis

- Subepidermal calcified nodule

- Tumoral calcinosis

- Osteoma cutis

Osteoma cutis is a cutaneous condition characterized by the presence of bone within the skin in the absence of a preexisting or associated lesion.