Metatarsal Stress Fracture

Oblique radiographic view of the foot shows transverse fracture lines of the proximal diaphyses of the forth and fifth metatarsals (arrows). Note sclerotic bone ends, periosteal reaction and minimal widening of the fracture gaps (degree of sclerosis is more on the forth digit)

Facts

• Spontaneous fractures of normal bone that result from summation of stresses
• Most common lower-extremity stress fracture
• Originally termed "march fracture" (seen in military recruits). Now seen in ballet, football, gymnastics and basketball
• Most common site = shaft (at diaphysis or neck)
• Increased incidence in pes cavus and pes planus foot

Radiography

• Often negative in early phase. May see thickening of cortex and small periosteal reaction
• Later, a fracture line with sclerotic bone ends, periosteal reaction, widening of fracture gap will be shown. 
• Late phase, the bone ends involved are entirely sclerotic 

References:

Schepsis AA, Busconi BD. Sports Medicine, 2006.

Baxter DE, Porter DA, Schon L. Baxter's the Foot and Ankle in Sport, 2008. 

Tibial Spine Fracture in Adults

A lateral knee radiograph of a 22-year-old man sustaining motor vehicle collision demonstrates an oval bone fragment (arrow) in the intercondylar region of the knee. There is complete separation between the fragment and the donor site with superior displacement of the fragment. Note hemarthrosis (asterisk).

Facts:

• Classically described in pediatric patients and considered the childhood equivalent of anterior cruciate ligament (ACL) ruptures in adults
• Forceful hyperextension of the knee resulting in avulsive force/tension on ACL, which inserts into the anterior tibial spine. Possibly with valgus stress or rotation. 
• In adults, most injuries occur in road-traffic accidents and are isolated
• Adults more likely to have associated tear of medial collateral ligament (MCL) or intra-articular fracture

Classification (Meyers and McKeever)

• Based on degree of displacement. Type II & III are most common
• Type I = incomplete avulsion of tibial spine without displacement
• Type II = incomplete avulsion with anterior elevation of the fragment
• Type IIIA = complete separation of fragment
• Type IIIB = rotated and comminuted fragment
• Generally, types I and II are managed conservatively while type III fractures are managed arthroscopically or with open reduction

References:

Kendall NS, et al. Fracture of the tibial spine in adults and children. J Bone J Surg [Br] 1992;74-B:848-52.

Rosen's Emergency Medicine - Concepts and Clinical Practice

Pulmonary Infarction

Chest x-ray demonstrates a peripheral airspace opacity (arrows) that has a wedge-shaped configuration and a blunt medial apex pointing toward the hilum

Coronal-reformatted CT images confirm the presence of airspace opacity in the right middle lobe (arrows) with an embolus in the corresponding segmental pulmonary artery (arrowhead)

Facts: 

• Pulmonary embolic obstruction can occur with or without resultant pulmonary infarction
• In pulmonary embolism with infarction, process begins as "incomplete" infarct (intra-alveolar hemorrhage without necrosis of alveolar wall), which can go on to necrosis "infarct" especially in patients with underlying unhealthy lung
• On CXR, infarct is seen as a wedge-shaped, pleural-based consolidation with a rounded convex apex directing toward the hilum "Hampton hump"
• Often occurs in lower lobes
• Heals with scar formation

Reference

Dalen JE. Pulmonary embolism: what have we learned since Virchow? Chest 2002; 122:1440-1456.

Medial Epicondyle Fracture of the Humerus

AP views of both elbows of an 18-year-old boy who sustained an injury to the right elbow.  There is an avulsion fracture (arrow) of the medial epicondyle of the right humerus. Radiograph of the left side demonstrates different areas of distal humeral structures from medial to lateral: medial epicondyle, trochlea, capitellum and lateral epicondyle. 

Facts:

• Common pediatric elbow fracture (3rd common, after supracondylar and lateral condylar fractures)
• Valgus strain at elbow joint
• Two main types: simple avulsion (1/2) and fracture-dislocation (occurring with lateral elbow dislocation; 1/2)
• Indications for surgery include 1) displaced fragment trapped in joint preventing reduction, 2) ulnar neuropathy, 3) valgus instability, 4) open fracture

Imaging:

• Look for displaced fragment trapped in the joint and degree of displacement because they might indicate surgery
• In patients less than 8 years, trochlea may be non-ossified and this may be confused with fracture of medial condyle, which is rarer and could be more complicated
• Another imaging Ddx is osteochondrosis

References:

Wilson JN. The treatment of fractures of the medial epicondyle of the humerus. J Bone J Surg 1960;42:778.

Gottschalk HP, Eisner E, Hosalkar HS. Medial epicondyle fracture sin the pediatric population. J Am Acad Orthop Surgeons 2012; 20:223.

Wheeless' Textbook of Orthopedics link

Sternal Osteomyelitis

Chest radiograph of a patient who had sternal pain, fever and discharge shows no obvious bony abnormality.

Sagittal STIR and coronal T1W MR images demonstrate bone marrow edema with soft tissue changes in the sternum and right sternoclavicular joint (arrows). 

Facts:

• Uncommon infection of the sternum and sternoclavicular joint
• Usually affecting drug addicts, individuals with history of recent subclavian catheter placement, and patients with chronic debilitating illnesses
• Inciting organisms vary widely depending on demographics
• High failure rates of medical treatment alone. Typical treatment includes surgical debridement and en bloc removal

Imaging

• Radiograph is rarely helpful
• CT may show bone destruction but this may be late because damage begins in the joint. Surrounding soft tissue abnormalities are often a useful sign.
• MRI much more sensitive to detect joint and bone changes that are similar in findings to other areas of bone/joint infection

Reference: 

Shields TW et al. General Thoracic Surgery, 7th edition, 2009.

Limbus Vertebra

LS spine x-ray, sagittal-reformatted CT and sagittal T1W MR images demonstrate a limbus vertebra in the anterosuperior corner of L4 vertebral body in this 32-year-old woman.

Facts

• Intrabody herniation of disc material at the margin of the endplate, occurs during spinal growth before skeletal maturity
• Herniation of nuclear material through the cartilaginous junction zone of ring apophysis may isolate this ossification center from the body margin, inhibiting osseous fusion to the vertebral body
• Up to 5% of cadavers
• Generally asymptomatic

Imaging

• Smoothly corticated triangular fragment of bone at the corner of the vertebral body
• Most common in midlumbar spine (L2-4) but can be at any level including cervical spine
• Most common at the anterosuperior corner of the vertebral body
• Typically displaced farther from margin of vertebral body

References:

Ghelman B, Freiberger RH. The limbus vertebra: an anterior disc hernation demonstrated by discography. AJR 1976; 127:854-855

Pelvic Ewing's Sarcoma

A pelvic radiograph of a 5-year-old girl shows a large lytic lesion in the left iliac bone (arrows).

An axial FDG PET/CT image shows high metabolic activity of the mass involving the left iliac bone with soft tissue component and bone destruction. A coronal T2W MR image reveals an extensive soft tissue mass with necrotic areas and involvement of the adjacent musculature. 

Differential Diagnosis

• Metastatic neuroblastoma. Given her age at five years old, this needs to be in differentials
• Ewing's sarcoma
• Telangiectatic osteosarcoma
• Osteomyelitis. Great mimics of aggressive-looking bone tumor. Symptoms may overlap with round-cell tumor, including fever

This case: Ewing's sarcoma by tissue diagnosis (+ve PAS and vimentin).

Facts: Ewing's Sarcoma

• Malignant round-cell tumors of the bone with neural cell origin
• Tumors of children and young adults, most between 10-20 years old. Less than 2% occur in children less than 5 years old
• Most common sites = femur >> pelvis
• Pelvic Ewing's -- bad prognosis because there is no anatomic barrier to tumor spread, close proximity to viscera and neurovascular bundles, prone to recur

Reference:

Bhagat S, Sharma H, Pillai DS, Jane MJ. Pelvic Ewing's sarcoma: a review from Swedish Bone Tumour Registry. J Orthop Surg 2008;16:333-8

Maisonneuve Fracture

Figure 1: AP and lateral ankle radiographs demonstrate a vertical fracture of the medial/posterior malleolus of the distal tibia without a fibular fracture.  

Figure 2: Full-length AP fibular radiograph shows a mildly displaced fracture of the fibular shaft at the junction between the proximal 1/3 and middle 1/3. 

Facts: Rotational Ankle Fractures

• Rotational ankle fractures are classified according to force direction applied to the foot, while the injured foot can be in a different position (supination/pronation, adduction/external rotation)
• AO/Weber classification: A, B, C fractures are differentiated by location of fibular fractures. 
• Fibular fracture below the syndesmosis = AO/Weber A (usually supination-adduction)
• Fibular fracture at the syndesmosis = AO/Weber B (~ supination and external rotation)
• Fibular fracture above the syndesmosis = AO/Weber C (~ pronation external rotation)

Facts: Maisonneuve Fractures

• High fibular fracture above the syndesmosis resulting from external rotation
• Often, there is injury to the medial ankle either a tranverse medial malleolar fracture, posterior malleolar fracture or disruption of the deltoid ligament
• Disruption of the syndesmosis and interosseous ligament up to the fibular fracture site
• Suspicious for this fracture if you see a 1) transverse medial malleolar fracture or 2) posterior malleolar fracture but no fibular fracture on the ankle radiographic series. In these situation, a full-length fibular radiograph should be taken

Reference:

Sakthivel-Wainford K. Self-assessment in limb x-ray interpretation, 2006

Rockwood CA, Green DP. Rockwood and Green's fractures in adults, 2005

Avian Spur

Facts:

• AKA supracondylar process of the humerus
• Congenital osseous/cartilagenous projection arising from the anteromedial surface of the distal humerus
• Found in 1% of population
• Associated with ligament of Struthers, which connects the process to the medial epicondyle (fibers of pronator teres may arise from this structure)
• Median nerve and brachial artery pass below this arch and may be compressed
• Fracture is possible but rare

Reference:

Egol KA, Koval KJ, Zuckerman JD. Handbook of fractures; 4th ed, 2010. 

Miliary Tuberculosis

A chest radiograph of a 37-year-old woman shows innumerable tiny nodules throughout both lungs in a uniform, symmetric distribution. 

Axial chest CT image confirms the presence of innumerable micronodules in a random distribution and uniformity.

Facts: Miliary TB

• Acute disseminated infection of mycobacterium tuberculosis via bloodstream, or progression of active TB (rupture of caseating lymph node or cavity into blood vessel)
• Primary site may be intra- or extrapulmonary, or may not be recognizable
• Life-threatening infection. Mortality 13-50%
• Any age, any immune status but poor immune individuals are at increased risk
• Only 30% have positive sputum examination
• Up to 60% have negative skin test

Imaging

• Chest radiograph (CXR) can be normal in early disease 
• CXR usually shows abnormality up to 10 days or more after clinical illness has started. CT can show it earlier
• "Miliary" nodules are tiny (<2 mm), discrete, about the same size. They may coalesce into patchy and more irregular opacities
• Nodules may take 2-3 months to fade even with adequate therapy
• No correlation between number or size of nodules and clinical health
• Lymph node enlargement, hepatosplenomegaly may be seen

Reference:

Palmer PES, Wambani SJ, Reeve P. The imaging of tuberculosis: with epidemiological, pathological, and clinical correlation, 2001. 

Avulsion of the Anterior Superior Iliac Spine

A pelvic radiograph demonstrates an avulsion fracture (arrows) of the right anterior superior iliac spine (ASIS) in a 14-year-old boy. 

Facts: Pelvic Avulsions

• Avulsion of pelvic bones usually found in young, skeletally immature athletes.
• Forceful contraction of the attached muscle while the athlete actively engages in kicking, running or jumping.
• Three major locations: ASIS (sartorius attachment), anterior inferior iliac spine (AIIS, rectus femoral attachment) and ischial tuberosity (hamstrings and adductor attachment).
• 50% of cases at ischial tuberosity, 23% ASIS, 22% AIIS (of all pelvic avulsions).
• Localized swelling and tenderness at the site of avulsion fracture. Limited motion from pain.

Imaging

• Plain radiography usually sufficient for diagnosis. 
• Comparison view helpful to ensure that abnormality is not a secondary center of ossification.
• Pitfalls: secondary ossification center, osseous mass seen as a delayed presentation mimicking neoplasm.

References

Davies AM, Johnson KJ, Whitehouse RW. Imaging of the hip & bony pelvis: techniques and applications. 

Beaty JH, Rockwood CA, Kasser R. Rockwood and Wilkins' fractures in children. 

Osteoid Osteoma

A frontal view of the right femur of a teenage boy demonstrates an ill-defined sclerotic area (arrows) in the proximal diaphysis with thickened cortex.

A coronal-reformatted CT image shows a well-defined lucency (arrow) within the central portion of sclerotic medulla. Within that lucency, a tiny calcific nidus is seen. Thickened cortex is also observed.

Facts: Osteoid Osteoma

• Self-limited benign osteogenic tumor consisting of a vascular mass (nidus) surrounded by reactive bone sclerosis
• Male predominance (male:female = 2:1). Teenagers and young adults (90% of cases between 5-30 years old)
• Characteristic pain referring to the nearest joint, worse at night. Pain is relieved by aspirin or NSAIDs
• Treatment options: surgical excision, CT-guided percutaneous resection or destruction of the nidus

Imaging Appearance

• Location: cortex, medulla or periosteum (anywhere but cortex most common)
• Long bones of lower extremity (esp femoral neck) most commonly affected. Almost never seen in flat bones and craniofacial bones
• Central lucent area (nidus) surrounded by sclerotic bone (nidus may be subtle and has variable degree of calcification)
• CT is helpful to identify the nidus (as in our case)
• MRI can be misleading because reactive bone marrow edema and soft tissue involvement may mimic malignancy

Our case: osteoid osteoma centered in the medullary cavity. The diagnosis was confirmed by CT (showing a lucent nidus with calcification) and clinical picture.

Reference:

Kadir S. Teaching Atlas of Interventional Radiology, 2005.

Vioria VJ, et al. Orthopaedic Pathology,

Lucencies and Cavitation in Bronchioloalveolar Carcinoma

• 

The chest radiograph shows an ill-defined focal opacity in the left lower lung zone.

Coronal-reformatted CT image done a few days after the chest radiograph reveals an irregular-shaped mass with internal lucencies that represent air bronchiologram and cavity. Desmoplastic reaction is also visualized.

Facts: BAC

• Well-differentiated adenocarcinoma of the lung
• Polymorphism
• Lepidic growth meaning spread of neoplastic cells in peripheral air space without destroying lung architecture
• On CT, it can be a nodule, mass, consolidation (segmental or lobar), multi centric or diffuse disease

Facts: Radiolucencies in BAC

• Important CT feature is internal radiolucencies but this is overlapping with other diseases
• Lucencies can represent air bronchiologram, bubbles of pseudocavitation, cavitation, serpentine, alveologram or thin-walled cystic lesions
• Bubbly lucencies or pseudocavitation is believed to be non-involved lobules, paracicatricial emphysema and fibrosis with honeycombing and localized bronchiectasis.

Our case: BAC with air bronchiologram and cavity.

Reference:

Gaeta M, et al. Radiolucencies and cavitation in bronchioloalveolar carcinoma: CT-pathologic correlation. Eur Radiol 1999;9:55-59.

Is Plain Radiography Sensitive Enough to Detect Pneumoperitoneum?

An upright chest radiograph shows a large amount of pneumoperitoneum under the right hemidiaphragm of a patient who has peptic ulcer perforation found at surgery.

Facts: Pneumoperitoneum & GI perforation

• Common
• Requires a breach through all layers of hollow viscus that would allow escape of intraluminal content into the peritoneal cavity
• Results in peritonitis, either localized or generalized

Detectability Rate of Imaging

• Plain radiography sensitivity ranges from 50% to 98% depending on the technique (upright chest, upright abdomen, left lateral decubitus, supine abdomen) and additional postural maneuver
• Recent study of 1,723 patients with GI perforation shows that radiography (either upright chest, upright abdomen or both) has positivity rate of almost 90%. 10% of radiographs did not show free air despite patients having GI perforation. Highest positivity rate was seen with gastric and duodenal perforation (94%), but lowest with appendiceal perforation (7%)

Reference:

Bansal J, Jenaw RK, Rao J, et al. Effectiveness of plain radiography in diagnosing hollow viscus perforation: study of 1,723 patients of perforation peritonitis. Emerg Radiol 2011 December.

Calcaneal Hemangioendothelioma

Authors: Bahri Nandini, M.D. and Sanjay B. Nathani, M.D. (Radiodiagnosis)

Editor: Rathachai Kaewlai, M.D.

Ankle radiograph shows a well defined lytic lesion with few septa in the anterior part of the calcaneus. There is cortical destruction at the medial and superior cortex of the calcaneus.

Sagittal PDT2W and coronal T1W MR images of the hindfoot show a lobulated mass with internal septa in the anterior part of the calcaneus with etension into the adjacent myofascial planes. The lesion is hypointense on T1W and hyperintense on T2W sequences.

Quick Facts:

• Hemangioendothelioma and angiosarcoma are a group of primary malignant vascular tumors of the bone, which are extremely rare
• Common locations: femur, tibia, pelvis and vertebra
• Age group: between 4th and 5th decade
• Imaging appearance: lytic lesion without sclerotic border, multilocular, bone expansion and laminated periosteal reaction
• Common differential diagnosis = aneurysmal bone cyst, simple bone cyst
  

The Case

• A 50 years old female presented with pain and swelling at left foot with no history of trauma. On clinical examination local tenderness at heal was present.
• Radiograph taken in oblique (fig 1) positions, showed a well defined, lobulated lytic lesion with a few internal septa in the anterior part of Calcaneum. The lesion extends and breaches the medial and superior cortex of calcaneum
• MRI study of foot and ankle using 1.5T Siemens Magnetom Essenza machine, which included T1, T2, PD and T2 fat suppressed axial, sagittal and coronal sequences were performed. On PDW sagittal and T1 coronal images the lesion appears well defined, lobulated , with few internal septas in the anteroinferior part of calcaneum and breaches the medial and superior cortex and involves the adjacent myofascial planes. The lesion is hyperintense on PDW images [figure 2 A] and hypointense in T1W coronal images [figure 2 B] Tibiotalar joint shows minimal joint effusion.
• On histopathological examination of the material obtained after intraoperative curettage of calcaneum findings were in favor of tumor of vascular origin.
• On the basis of the clinical, radiological and histopathological findings, presumptive diagnosis of Calcaneal Hemangioendothelioma was considered.

Discussion

• Hemangioendothelial sarcoma includes hemangioendothelioma and angiosarcoma, which encompasses a group of primary malignant vascular tumors in bone that vary from the malignant capillary and cavernous blood vessel formation to the proliferative endothelial sarcomas. Hemangioendothelioma is a tumor of blood vessels, in which endothelial cells are seen as predominant cell
• Primary malignant vascular tumors in bone are extremely rare(less than 1% of all bone tumors). It can occur in all age groups; however most of the patients are between 4^th and 5^th decades of life. Most commonly affected bone is Femur (16%), followed by Tibia(14%), pelvis(12%), vertebra(10%). Other rare sites are foot, hand, forearm bones and clavicle. The patient may not experience any specific symptoms or signs. Patient may present with Pain or occasionally swelling. Hemangioendothelioma shows multicentricity of lesions in the bones of the same extremity. On Radiographs, the solitary lesion is well circumscribed, lytic with no surrounding sclerosis or matrix mineralization, which shows internal septa which may be scant or incomplete. Occasionally it may show multilocular appearance. The tumor causes expansion, thinning and erosion of the cortex and often associated with a mild laminated periosteal reaction.
• On MR imaging, the lesion appears well defined, multilocular which is hyperintense on T2W and PDW images and hypointense on T1W images with internal septa. The lesion involves the surrounding soft tissue and involvement of multiple bones can occur.
• The etiology of unicameral bone cysts of the calcaneum is an enigma, just as it is with these lesions in other bones. Popular theories regarding the origin of bone cysts have been related to the long bones and the juxtaposition of the cyst to the growth plate
• Most commonly considered differential diagnoses are Simple Bone Cyst, Aneurysmal Bone Cyst. That can be differentiated by moth eaten erosion pattern and irregular margins of Hemangioendothelial sarcoma.

This case is a 50-year-old female with pathological findings of a tumor of vascular origin.

References:

1. Ackerman LV, Spujat HJ. Tumors of bones and cartilage. Atlas of tumor pathology. Armed Forces Institute of Pathology, Washington, DC, 1962

2. Jaffe HL, Lichtenstein L. Solitary unicameral bone cyst with emphasis on the roentgen picture. Arch Surg 1942;44:1004-1025

3. Smith RW, Smith CF. Solitary unicameral bone cyst of the calcaneum: a review of twenty cases. J Bone Joint Surg Am 1974;56:49-56.

About Authors: Drs. Nandini and Nathani work for the Department of Radiodiagnosis, G.G. Hospital, Jamnagar, Gujarat in India. Their work does not have any support for the work in the form of grants, equipments or drugs.

Triquetral Fracture

A lateral wrist radiograph shows a small bone fragment (arrow) dorsum to the wrist with overlying soft tissue swelling.

Facts:

• Second most common carpal bone fracture
• Two main types: dorsal chip fracture and body fracture
• Dorsal chip fracture (like in our case ) believed to be due to forceful impingement of the triquetrum during wrist hyperextension
• Body fracture frequently associated with perilunate dislocation (direct blow)
• Pain and swelling localized at the dorsum of the wrist where triquetrum is located
• Complication: motor branch of ulnar nerve injury

Imaging

• Chip fracture best seen on lateral radiograph with hand in flexion
• Body fracture best seen on AP and oblique radiographs
• Fractures are possibly underreported. CT can help in suspected cases.

Reference:

Simon RR, Koenigsknecht SJ. Emergency orthopedics: the extremities, 2001.

Calcification in Lung Nodule

A spot chest radiographic view of the left lower lung zone (with a nipple marker) shows a 1-cm nodule (arrow) in the lung base just medial to the nipple marker.

Non-contrast CT confirms the presence of a nodule in the left lower lobe (arrow) that contains a central calcification.

Lung Nodule Calcification

• Up to 6% of lung cancer have calcification. Therefore, calcium in a nodule does not exclude possibility of lung cancer
• Suspected malignant nodule if calcium is.... eccentric, amorphous or it involves only a small portion of the nodule
• Benign: central (>10% of cross-sectional area of nodule), diffuse and laminated calcification
• Nodules that are nonsolid or partly solid are more often malignant

Our case: benign nodule, likely a granuloma.

Reference:

Hodler J, von Schulthess GK, Zollikofer ChL. Diseases of the Heart, Chest & Breast 2011-2014. Springer-Verlag Italia 2011.

Unilateral Diaphragmatic Elevation

An AP chest radiograph shows elevation of the right hemidiaphragm.

Unilateral Diaphragmatic Elevation: Differentials

• Lung/pleural disease: Pneumonectomy, lobectomy, pleurisy, subpulmonic effusion
• Diaphragm disease: Phrenic nerve palsy / eventration
• Abdominal disease: Hepatomegaly / hepatic mass / abdominal neoplasm / distended stomach

US and CT images demonstrate a very large cyst in the right lobe liver as a cause of elevated right hemidiaphragm.

Intussusception Reduction

A "scout" radiograph before intussusception reduction procedure shows a soft tissue mass (arrows) in the right upper quadrant representing the intussusception. There is no free air.

Contrast enema for reduction shows the intussusception (arrows) in the right upper quadrant. It was successfully reduced.

Facts

• Image-guided liquid or air reduction of intussusception is the treatment of choice
• Contraindications for image-guided reduction = peritonitis, free intraperitoneal air due to perforation, in shock or sepsis
• Choice between air, liquid, contrast enema reduction of intussusception depends on radiologist experience and local preference/practice. Most radiologists prefer to use air and it is now generally accepted as the technique of choice
• Air pressure: between 80 and 120 mmHg
• Contrast: bag positioned approximately between 3 ft and 6 ft above the patient
• Reduction rate between 80% to 95%

Preparation for Reduction

• Notify the referring physician and surgeon
• Patient must be stable, well-hydrated and has no evidence of peritonitis
• IV line in place
• A large-bore needle at hand (if you use air reduction)

Complications

• Perforation rates with air enema less than 1%
• Recurrence 10% of cases

Reference:

1. Daldrup-Link HE, Gooding CA. Essentials of Pediatric Radiology: A Multimodality Approach, 2010.

2. Hodler J, Von Schulthess GK, Zollikofer CL. Diseases of the Abdomen and Pelvis 2010-2013: Diagnostic Imaging and Interventional Techniques, 2010.

Tension Pneumothorax

Chest radiograph shows a very large left pneumothorax (stars) causing mass effect to the mediastinum (shifting, arrows), deep costophrenic sulcus and collapsed left lung.

Facts

• One-way valve effect causing continuous air collection within pleural space resulting in collapse of the lung on the affected side and compression of opposite lung
• Poor lung compliance and increased airway pressure leads to ineffective gas exchange
• Mass effect on mediastinal structures cause decreased venous return and decreased cardiac output
• Symptoms and signs: chest pain, dyspnea, respiratory distress, tachypnea, dyspnea, cyanosis, elevated jugular venous pressure, absent breath sounds, tracheal deviation and hemodynamic compromise
• This is a clinical diagnosis and confirmation with radiography is not recommended. Needle decompression should be immediately performed

Imaging

• Again, this is a clinical diagnosis. Yet imaging may be performed and shows large pneumothorax, mediastinal shifting, flat hemidiaphragm

Reference:

Greenberg MI. Greenberg's Text-atlas of Emergency Medicine, 2005.