Hypertrophic Osteoarthropathy

Hypertrophic osteoarthropathy (HO), formerly and incorrectly referred to as hypertrophic pulmonary osteoarthropathy, has primary and secondary forms. The primary form (pachydermoperiostosis) is often familial and is more commonly seen in males.

The secondary form can be seen in a variety of pulmonary and hepatic conditions, including:

• Lung cancer
• Mesothelioma
• Carcinomas of liver and gut
• Inflammatory bowel disease
• Liver cirrhosis
• Congenital cyanotic heart disease
• Pulmonary fibrosis
• Empyema
• Graves disease
• Thalassemia

Patients can present with clubbing of fingers, periostosis of distal long bones, thickening of skin over face and ankles, gynecomastia, and arthritis and synovitis. The synovitis is accompanied by a viscous, non-inflammatory effusion.

Various etiologies have been proposed, but the most recent thought is that it is due to arteriovenous shunting (e.g., in the liver, lung, or various tumors). The idea is that unfragmented megakaryocytes get delivered to distal sites in systemic circulation instead of being filtered in the lungs. This leads to production of growth factors (PDGF and VEGF), which lead to angiogenesis, endothelial hyperplasia. In certain lung tumors, there is de novo production of these growth factors by tumor, which makes it to the peripheral circulation.

A neurogenic role has also been proposed. This is supported by the fact that pain and deformity resolve with peripheral vagotomy in both primary and secondary forms, even with the primary tumor intact.

Differential diagnosis for Multifocal Periostitis in Adults and children were covered earlier.

References

Armstrong DJ, et al. Hypertrophic pulmonary osteoarthropathy (HPOA) (Pierre Marie-Bamberger syndrome): two cases presenting as acute inflammatory arthritis. Description and review of the literature. Rheumatol Int. 2007 Feb;27(4):399-402.

Causes of Hepatic Capsular Retraction

Peripheral Cholangiocarcinoma

• malignant tumor arising from interlobular bile ducts
• peripheral enhancement on arterial phase CECT with gradual centripetal fill in
• delayed enhancement is common due to fibrotic regions within mass
• may have dilated bile ducts upstream from the lesion

Confluent Hepatic Fibrosis

• occurs in the setting of cirrhosis
• usually in the medial segment of the left lobe and/or anterior segment of the right lobe
• peripheral wedge shaped regions of low attenuation on CECT that show delayed enhancement
• biliary ductal dilatation not seen

Metastases

• treated adenocarcinoma (usually colorectal, breast) can cause hepatic capsular retraction 
• regions of fibrosis (pseudo-cirrhosis) may also be seen

REFERENCES

Fennessy FM, Moretele KJ, Kluckert T, et al. Hepatic capsular retraction in metastatic carcinoma of the breast occurring with increase or decrease in size of subjacent metastasis. AJR Am J Roentgenol 2004;182(3):651-5.

Lee JW, Kim S, Kwack SW, et al. Hepatic capsular and subcapsular pathologic conditions: demonstration with CT and MR imaging. Radiographics 2008;28:1307-23.

Lipson JA, Qayyum A, Avrin DE, et al. CT and MRI of hepatic contour abnormalities. AJR Am J Roentgenol 2005;184(1):75-81.

SATCHMO

The differential diagnosis of a suprasellar mass can be remembered through the SATCHMO mnemonic.

S - suprasellar/sellar adenoma, sarcoid
A - aneurysm, arachnoid cyst
T - teratoma
C - craniopharyngioma
H - hamartoma (of the tuber cinereum), hypothalamic glioma
M - meningioma
O - optic nerve glioma

The above image is from a patient who presented to the ER several times after multiple motor vehicle accidents. On clinical exam he was found to have visual field defects. NECT demonstrates a hyperattenuating sellar mass. Post operative diagnosis was pituitary macroadenoma.

Teardrop Bladder

A contrast-filled bladder that has a teardrop shape (also referred to as pear-shaped) indicates circumferential extrinsic compression. The differential diagnosis includes:

• presence of pelvic fluid
• hematoma
• lymphocele
• urinoma
• abscess
• pelvic lipomatosis
• usually seen in black males with hypertension
• iliopsoas muscle hypertrophy
• retroperitoneal fibrosis
• lymphoma
• vascular dilatation
• aneurysm
• collateral vessel development

REFERENCES

Ambos MA, Bosniak MA, Lefleur RS, et al. The pear-shaped bladder. Radiology 1977;122:85-8.

Dyer RB, Chen MY, Zagoria RJ. Classic signs in uroradiology. Radiographics 2004;24:S247-80.

Red Bone Marrow Reconversion

Bone marrow is primarily red (composed of hematopoietic elements) at birth and converts to yellow with skeletal maturation. The two types of marrow differ in their composition: red marrow is approximately 40% water and 40% microscopic fat, while yellow marrow is approximately 80% fat. This lends to the differing MR imaging appearances of red and yellow marrows.

Reversal of a normal marrow conversion pattern (marrow reconversion) can occur with various stressors. Specifically, reconversion occurs in healthy individuals with changing metabolic demands, for example those enlisting in an athletic training program or altitude climbers. Slightly different is the idea of marrow repopulation which happens in patients with a chronic illness such as sickle cell disease or thalassemia. A third cause of increased red marrow in adults is marrow stimulation which occurs in patients who are receiving red cell and/or granulocyte stimulating factors.

The differential diagnosis for increased red marrow in adults includes marrow deposition disease (Gaucher's), myelofibrosis, leukemia and lymphoma.


REFERENCES
Poulton TB, Murphy WD, Durek JL, et al. Bone marrow reconversion in adults who are smokers: MR imaging findings. AJR Am J Roentgenol 1993;161(6):1271-21.
Zajick DC Jr, Morrison WB, Schweitzer ME, et al. Benign and malignant processes: normal values and differentiation with chemical shift MR imaging in vertebral bodies. Radiology 2005;237(2):590-6.

Benign Neoplasms of the Spleen

1. Splenic cysts
• true cyst - has endothelial lining
• epidermoid
• parasitic
• pseudocyst - lacks endothelial  lining 
• post traumatic - most common
• both are well defined masses, attentuation similar to water on CT, do not enhance with contrast administration, high signal on T2WI
2. Hemangioma
• most common benign neoplasm
• US: small cystic masses, may show flow on color Doppler
• CT: hypodense on NCECT, post contrast images show early centripetal nodular enhancement with delayed uniform enhancement
• MR: hypointense on T1WI, hyperintense on T2WI
• diffuse hemangiomatosis
• Klippel-Trenaunay-Weber
• Kasabach-Merritt-like
• Beckwith-Weidemann
3. Hamartoma
• associated with tuberous sclerosis
• heterogeneously hyperintense relative to spleen on T2WI
• diffuse enhancement in early post contrast phase that becomes more uniform on delayed images
4. Lymphangioma
• US: well defined, hypoechoic mass, internal septations, may have echogenic debris
• CT: splenomegaly, single or multiple hypodense masses, may have peripheral calcifications, no enhancement post contrast
• MR: hypointense T1WI, hyperintense T2WI

REFERENCES

Elsayes KM, Narra VR, Mukundan G, et al. MR imaging of the spleen: spectrum of abnormalities. Radiographics 2005;25:967-82.

Urrutia M, Mergo PJ, Ros LH, et al. Cystic masses of the spleen: radiologic-pathologic correlation. Radiographics 1996;16:107-29.

Fibrosing Mediastinitis

Fibrosing mediastinitis (FM) is due to abnormal proliferation of collagen and fibrous tissue in the mediastinum. It can present either focally or diffusely with the latter type involving multiple mediastinal compartments. Causes are either idiopathic or secondary to granulomatous infection (Histoplasmosis in the United States). 

FM is the most common benign cause of SVC obstruction. Imaging findings include a hilar or mediastinal mass causing mediastinal widening. The right paratracheal region is the most common location for occurrence of a mass. Focal FM tends to have calcified masses whereas calcification is less common in diffuse FM. 

Differential considerations include:

• lymphoma
• bronchogenic carcinoma - usually older patient, doesn't calcify

REFERENCES
Rossi SE, McAdams HP, Rosado-de-Christenson ML, et al. Fibrosing mediastinitis. Radiographics 2001;21:737-57.

Cervical Spine Change in Rheumatoid Arthritis

60-80% of patients with rheumatoid arthritis have cervical spine involvement. Manifestations include:

• atlantoaxial subluxation - do flexion/extension films, increased atlantodens interval
• multilevel, "stepladder" subluxations may be seen
• erosion of the dens
• calcified pannus around the dens is NOT rheumatoid arthritis - usually CPPD
• cranial settling - decreased distance from occiput to C2
• due to facet joint erosions
• spinous process erosions
• erosions at the foramen of Luschka

REFERENCES 
Sommer OJ, Kladosek A, Weiler V, et al. Rheumatoid arthritis: a practical guide to state-of-the-art imaging, image interpretation, and clinical implications. Radiographics 2005;25:381-98.

Intracranial Hypotension and Diffuse Dural Enhancement

Intracranial hypotension refers to decreased CSF pressure leading to a headache (usually orthostatic). The four main imaging findings are:

1. downward displacement of the midbrain
2. diffuse, smooth dural enhancement
3. distended dural sinuses
4. subdural hematoma or hygroma

Absence of one of these signs does not preclude the diagnosis.

The dural enhancement in intracranial hypotension is pachymeningeal (dura-arachnoid) and is seen along the inner table of the skull, as opposed to leptomeningeal enhancement (arachnoid-pia) which is seen on the surface of the brain.

The differential for dural enhancement includes:

1. meningitis - leptomeningeal enhancement
2. dural metastases - scattered, "bumpy" enhancement
3. granulomatous disease (sarcoid, TB) - nodular enhancement
4. meningioma with focal enhancement of the dural tail
5. postoperative changes - transient

REFERENCES

Smirniotopoulous JG, Murphy FM, Rushing EJ, et al. Patterns of contrast enhancement in the brain and meninges. Radiographics 2007;27:525-51.

Tumors Identified via Selective Catheterization of the External Carotid Artery

1. Juvenile nasopharyngeal angiofibroma:

• young boys presenting with epistaxis 
• vascular hamartoma
• embolization is therapeutic

2. Carotid body paraganglioma:

• found at the bifurcation of the carotid artery where they splay its internal and external branches
• prolonged, intense tumor blush
• resectability depends on angle between ICA and ECA
• patients often left with hoarseness due to proximity of vagus nerve
• preoperative embolization may be considered

3. Meningioma:

• highly vascular extra-axial neoplasm 
• core is supplied by branches of the ECA while periphery is supplied by the ICA
• "spoke wheel" appearance on angiogram
• resection is usually curative
• large tumors may be embolized prior to resection

REFERENCES

Pribram HFW. Selective catheterization of the external carotid artery. Radiology 1966;87:315-20.

Roberson GH, Price AC, Davis JM, et al. Therapeutic embolization of juvenile angiofibroma. AJR Am J Roentgenol 1979;133:657-63.

Wieneke JA, Smith A. Paraganglioma: carotid body tumor. Head Neck Pathol 2009;3(4)303-6.

Wilson G, Weidner W, Hanafee W. The demonstration and diagnosis of meningiomas by selective catheter angiography. AJR Am J Roentgenol 1965;95(4):868-73.

Caroli's Disease and Syndrome

Caroli's Disease

• autosomal recessive abnormality in ductal plate development
• communicating cavernous biliary ectasia 
• US will show:
• dilated intrahepatic bile ducts that are saccular or fusiform
• outpouchings may contain sludge/calculi due to biliary stasis 
• central dot sign - color Doppler shows flow in the portal triads surrounded by the dilated ducts
• ERCP/MRCP will show dilated ducts that communicate with the central biliary tree

Caroli's syndrome is Caroli's disease + congenital hepatic fibrosis.

REFERENCES

Levy AD, Rohrmann CA, Murakata LA, et al. Caroli's disease: radiologic spectrum with pathologic correlation. AJR Am J Roentgenol 2002;179:1053-7.

Segmental Testicular Infarction

The presentation of an acute scrotum in the emergency setting typically leads to a work up for testicular torsion with ultrasound imaging. Accurate diagnosis of acute testicular torsion is important because the risk of global testicular infarction increases with time from onset of symptoms. 

Segmental testicular infarction is a rarer entity that is not well described in the literature. Ultrasound will demonstrate wedge shaped, hypoechoic regions in the testes with absence of vascular flow. The differential diagnosis for this finding is:

• polycythemia vera
• intimal hyperplasia of the spermatic artery
• sickle cell anemia
• vasculitis
• systemic lupus erythematosus
• polyarteritis nodosa
• venous thromboses (in hypercoagulable states)
• severe epididymo-orchitis that is unresponsive to treatment
• trauma

Differentiation between these entities and testicular torsion is important because treatment of the underlying condition (i.e. with steroids for polyarteritis nodosa) can prevent an unnecessary orchidectomy.


REFERENCES
Fernandez-Perez GC, Tardaguila FM, Velasco M, et al. Radiologic findings of segmental testicular infarction. AJR Am J Roentgenol 2005;1587-93.
Sriprasad S, Kooiman GG, Muir GH, et al. Acute segmental testicular infarction: differentiation from tumor using high frequency colour Doppler ultrasound. BJR 2001;74:965-7.

Cystic and Solid Lesions of the Cardiophrenic Space

The cardiophrenic space is located at the base of the mediastinum and is defined by the base of the heart, the diaphragm, and the chest wall. Normally, this space is occupied by fat although both benign and malignant lesions can be found in this location.

Cystic Lesions

1. Pericardial cysts
• benign
• usually in the right cardiophrenic space
• CT: well defined, smooth-walled cyst filled with simple fluid
• MR: high signal intensity on T2WI
2. Hydatid cyst
• rare
• may be a herniated hepatic hydatid cyst
• CT: uni- or multilocular cyst with peripheral mural calcifications
• MR: mother cyst (the matrix) is usually intermediate signal intensity on T1WI; daughter cysts are high signal intensity on T2WI
3. Thymic tumors with cystic components

Solid Lesions

1. Lymphadenopathy
• > 8mm in short axis diameter is considered pathologic
• lymphoma is most common cause
2. Thymoma

REFERENCES

Pineda V, Andreu J, Caceres J, et al. Lesions of the cardiophrenic space: findings at cross-sectional imaging. Radiographics 2007;27:19-32.

Pepper Pot Skull

Pepper pot skull (or salt and pepper skull) refers to a granular, mottled appearance of the calvarium with tiny hyperlucent areas. Other descriptive terms for this finding include ground glass texture and loss of differentiation between the inner and outer tables of the skull. This appearance is attributed to the resorption of trabecular bone and is seen in hyperparathyroidism. While some may use the term pepper pot skull to describe the lytic skull lesions seen in multiple myeloma, these lesions typically produce larger hyperlucent areas in the calvarium and are often referred to as "punched out" lucencies.

I recommend taking a look at the reference below - a cute reminder of all of the "food signs" in radiology.

REFERENCES
Roche CJ, O'Keeffe DP, Lee WK, et al. Selections from the buffet of food signs in radiology. Radiographics 2002;22:1369-84.

Intramedullary Osteosclerosis

A nonhereditary condition that effects the long bones of the lower extremities (tibia > femur, fibula). On imaging studies it presents with endosteal sclerosis extending into the medullary canal, possibly obliterating the canal. There is no associated periosteal reaction or soft tissue swelling. Bone scan will show intense radiopharmaceutical uptake.This condition is more common in women and usually presents as pain that is exacerbated by activity.

Differential diagnosis:
1. Ribbing disease - may look exactly the same. The main difference is that Ribbing disease tends to have a familial inheritance pattern (thought to be autosomal recessive).
2. Stress fracture - usually a focal sclerosis and periosteal reaction will be present.
3. Sclerotic metastases - patchy, discontinuous presentation, population tends to be older.
4. Progressive diaphyseal displasia (Camurati-Engelmann disease) - presents in young boys, has skull and vertebral body involvement, disease begins in the diaphysis of long bones and may extend to the metaphysis, has periosteal and endosteal sclerosis. 
5. Melorheostosis (Leri-Weill disease) - a sclerosing bone dysplasia which presents unilaterally in a long bone of the upper or lower extremity and may have associated soft tissue calcifications.

REFERENCES
Balkissoon ARA and Hayes CW. Intramedullary osteosclerosis. Radiology 1999;212:708-10.
Chanchairujira K, Chung CB, Lai YM, et al. Intramedullary osteosclerosis: imaging features in nine patients. Radiology 2001;220:225-30.

Drugs and Cardiac FDG Uptake

Certain drugs and patient factors can affect cardiac uptake of FDG.

Drug	Effect	Comment
Insulin	↑	Similar to the effect of eating close to FDG administration. Will also cause diffuse increase in muscle uptake and a decrease in liver uptake.
Bezafibrate	↑	Fibrate drug used for hyperlipidemia.
Benzodiazepines	↑
Levothryoxine	↓
Metformin	↓	Shown above. Increases colonic FDG uptake and can result in a competitive decrease in cardiac FDG uptake.

In addition to the above, certain patient factors can increase cardiac FDG uptake: Male gender, younger patients (< 30 years), fasting duration of <5 hours, and patients with heart failure tend to have higher cardiac FDG uptake.

References

• Israel O, Weiler-Sagie M, Rispler S, Bar-Shalom R, Frenkel A, Keidar Z, Bar-Shalev A, Strauss HW. PET/CT quantitation of the effect of patient-related factors on cardiac 18F-FDG uptake. J Nucl Med. 2007 Feb;48(2):234-9.
• Maurer AH, Burshteyn M, Adler LP, Steiner RM. How to differentiate benign versus malignant cardiac and paracardiac 18F FDG uptake at oncologic PET/CT. Radiographics. 2011 Sep-Oct;31(5):1287-305.

Pulmonary Alveolar Microlithiasis

Pulmonary alveolar microlithiasis is a rare autosomal recessive disease that is caused by impaired transfer of phosphorus ions from the alveolar space into type II pneumocytes. This leads to the development of microliths composed of calcium and phosphorus (calcospherites) in the alveoli.

Men and women are affected at an equal rate, and patients tend to be younger than 50 years of age at diagnosis. Most patients have at least one sibling with the disease, and there is a high rate of consanguineous marriages in affected families.

Patients typically present with progressive dyspnea, which, after a protracted course, progresses to pulmonary fibrosis, end-stage lung disease, and chronic pulmonary heart disease.

Initial laboratory evaluation usually reveals no underlying disorder calcium metabolism, and pulmonary function testing reveals a restrictive pattern of lung disease and decreased diffusion capacity (transfer factor).

Radiographs reveal fine calcific micronodules in a diffuse (sandstorm) pattern, but with a more dense involvement of the lower zones (thought to be due to the larger surface area and greater thickness of this part of the lungs). There is usually silhouetting of the mediastinal and diaphragmatic borders and a linear lucency between the ribcage and parenchyma (reflecting subpleural cystic changes). Small apical bullae with or without an associated pneumothorax may also be present.

The findings are more subtle in children. Nodular calcific densities are less prominent on children’s chest radiographs and the major finding may be ground-glass opacities.

HRCT reveal widespread involvement of both lungs with microliths, with a predisposition for the posterior segments of the lower lobes, anterior segments of the upper lobes, and the medial aspects of the lungs.

Confluent calcifications may also be seen, and are often found in the upper lobes. There is also micronodulation and thickening of the interlobular septa and bronchovascular and subpleural interstitium.

Multiple small, thin-walled subpleural cysts can also be seen and are responsible for the lucent subpleural line seen on radiographs. Pleural calcifications have also been described.

When extensive, the calcifications can result in interlobular septal thickening. Microliths smaller than 1 mm can produce a ground-glass appearance. Together, these can give an appearance similar to crazy paving.

In children, a ground-glass pattern may predominate, and microliths are seen to a lesser degree.

Differential considerations include:

• Metastatic calcification: For example, in chronic renal failure and orthotopic liver transplantation.
• Dystrophic calcification: Caused by granulomatous disorders (silicosis, sarcoidosis), DNA viruses, parasitic infections, and pulmonary amyloidosis.
• Pulmonary ossification: Multiple causes. Most pimped: chronic chronic mitral stenosis.

References

• Chan ED, Morales DV, Welsh CH, McDermott MT, Schwarz MI. Calcium deposition with or without bone formation in the lung. Am J Respir Crit Care Med. 2002 Jun 15;165(12):1654-69.
• Gasparetto EL, Tazoniero P, Escuissato DL, Marchiori E, Frare E Silva RL, Sakamoto D. Pulmonary alveolar microlithiasis presenting with crazy-paving pattern on high resolution CT. Br J Radiol. 2004 Nov;77(923):974-6.
• Helbich TH, Wojnarovsky C, Wunderbaldinger P, Heinz-Peer G, Eichler I, Herold CJ. Pulmonary alveolar microlithiasis in children: radiographic and high-resolution CT findings. AJR Am J Roentgenol. 1997 Jan;168(1):63-5.
• Siddiqui NA, Fuhrman CR. Best cases from the AFIP: Pulmonary alveolar microlithiasis. Radiographics. 2011 Mar-Apr;31(2):585-90.

Central Venous Obstruction in the Chest

Collateral vessels can be recruited to bypass central venous obstruction in the chest via three routes. More central obstructions (superior vena cava) tend to recruit more inferior collaterals, while the more peripheral obstructions (subclavian or brachiocephalic veins) tend to recruit more superior collaterals.

The three routes are:

• Superior route: Seen with subclavian or brachiocephalic vein obstruction. Blood flows via through the ipsilateral external jugular vein into horizontal veins that communicate across the midline via the transverse arch of the anterior jugular venous system. Once on the contralateral side, blood flows into the external jugular vein into the subclavian vein, and finally into the superior vena cava.
• Posterior route: Seen in cases of obstruction at the level of the supraazygos superior vena cava. This leaves the azygos vein as a conduit for blood to get into the superior vena cava. Blood from the head and neck flows through paravertebral collaterals into intercostal and paravertebral veins and then the superior intercostal vein, which drains into the azygos vein.
• Anterolateral: Seen in cases of central superior vena cava obstruction (shown above). Blood flows through anterior intercostal, internal mammary (pink arrow), and long thoracic veins, which, flow to the inferior vena cava (green arrow) via pericardiophrenic (yellow arrow), musculophrenic (blue arrow), lumbar, and hepatic veins. The internal mammary vein can also connect to the left portal vein via the paraumbilical vein and result in increased activity or enhancement in segment IV of liver (white arrow) and is the basis of the focal hepatic hot spot sign on ^99mTc sulfur colloid "liver and spleen" scans. IN the image above, we also see aortopulmonary window collaterals (red arrow) that drain into the infraazygos superior vena cava(S), in this patient with combined infraazygos superior vena cava and azygos vein obstruction.

References

• Dickson AM. The focal hepatic hot spot sign. Radiology. 2005 Nov;237(2):647-8.
• Gosselin MV, Rubin GD. Altered intravascular contrast material flow dynamics: clues for refining thoracic CT diagnosis. AJR Am J Roentgenol. 1997 Dec;169(6):1597-603.
• Lee KR, Preston DF, Martin NL, Robinson RG. Angiographic documentation of systemic-portal venous shunting as a cause of a liver scan ""hot spot'' in superior vena caval obstruction. AJR Am J Roentgenol. 1976 Oct;127(4):637-9.
• Godwin JD, Chen JT. Thoracic venous anatomy. AJR Am J Roentgenol. 1986 Oct;147(4):674-84.

Button Sequestrum

The button sequestrum is a lucent bony lesion with an internal opacity. It is a nonspecific finding that is an uncommon/rare manifestation of the following conditions:

• Langerhans cell histiocytosis of bone:
• Osteomyelitis:
• Fibrous sarcomas of bone: Includes fibrosarcoma, desmoplastic fibroma and malignant fibrous histiocytoma of bone.
• Lymphoma:
• Intraosseous Lipoma: Lucent lipoma with partial calcification.
• Tuberculous osteitis:
• Radiation necrosis:
• Metastatic carcinoma:
• Fibrous dysplasia:
• Epidermoid and dermoid cyst:
• Hemangioma:
• Meningioma:

References

• Krasnokutsky MV. The button sequestrum sign. Radiology. 2005 Sep;236(3):1026-7.

Cartilage Lesions by Age and Location

Image of the humerus from Human skeleton front en.svg

Once you've made the determination that a long bone lesion is a chondroid tumor, age and location can help narrow your differential diagnosis.

Chondroblastoma and clear-cell chondrosarcoma are epiphyseal lesions that can be indistinguishable. While chondroblastomas tend to affect a younger age group than clear-cell chondrosarcomas, there is some overlap.

Chondromyxoid fibromas are rare metaphyseal lesions that may not have an obvious chondroid matrix on radiography. They most commonly occur in the proximal tibia.

Enchondromas and chondrosarcomas are diaphyseal lesions that have characteristic appearances at their extremes. However, there can be significant overlap, especially between enchondromas and low-grade chondrosarcomas.

Please note that these are rough guidelines: Tumors don't read this blog.

References

• Greenspan A, Jundt G, Remagen W. Cartilage (Chondrogenic) Lesions. In Differential Diagnosis of Orthopaedic Oncology, 2nd Edition. 2007 Lippincott Williams & Wilkins; pp 162-255.
• Kindblom LG. Bone Tumors: Epidemiology, Classification, Pathology. in Imaging of Bone Tumors and Tumor-Like Lesions. Davies AM, Sundaram M, and James SLJ (eds). Springer-Verlag Berlin Heidelberg (2009); pp 1-4.