Pseudomonas aeruginosa is a common Gram-negative, rod-shaped bacterium that can cause disease in plants and animals, including humans. It is citrate, catalase, and oxidase positive. P. aeruginosa uses the virulence factor exotoxin A to inactivate eukaryotic elongation factor 2 via ADP-ribosylation in the host cell, much the same as the diphtheria toxin does. Without elongation factor 2, eukaryotic cells cannot synthesize proteins and necrotise. The release of intracellular contents induces an immunologic response in immunocompetent patients.

The lowest part of the pleural cavity is the costodiaphragmatic recess and it the space in which the pleural fluid will accumulate when the patient sits up.
The cupola is part of the pleural cavity that extends into the root of the neck above the first rib.
The costomediastinal recess is the junction at which the costal pleura becomes the mediastinal pleura.
The middle mediastinum is the part of the mediastinum that is occupied by the heart.
The hilar reflection is the point where the mediastinal pleura is reflected to continue on as the visceral pleura.

Hypertension in a young patient without any obvious cause should be investigated.

A pheochromocytoma is a catecholamine-secreting tumour typically located in the adrenal medulla. Pheochromocytomas are usually benign (∼ 90% of cases) but may also be malignant. Classic clinical features are due to excess sympathetic nervous system stimulation and involve episodic blood pressure crises with paroxysmal headaches, diaphoresis, heart palpitations, and pallor. However, a pheochromocytoma may also present asymptomatically or with persistent hypertension. Elevated catecholamine metabolites in the plasma or urine confirm the diagnosis, while imaging studies in patients with positive biochemistry are used to determine the location of the tumour. Surgical resection is the treatment of choice, but is only carried out once alpha blockade with phenoxybenzamine has become effective.

Pheochromocytoma is said to follow a 10% rule:

,10% are extra-adrenal
,10% are bilateral
,10% are malignant
,10% are found in children
,10% are familial
,10% are not associated with hypertension
,10% contain calcification

Urinary incontinence is the involuntary excretion of urine from one’s body. It is often temporary and it almost always results from an underlying medical condition. Several types include:
– Stress incontinence is the voiding of urine following increased abdominal pressure e.g. laughing, coughing, pregnancy etc. It is the most common form of incontinence in women, most commonly due to pelvic floor muscle weakness, physical changes from pregnancy, childbirth and menopause. In men it is a common problem following a prostatectomy. Most lab results such as urine analysis, cystometry and postvoid residual volume are normal.
– Urge incontinence is involuntary loss of urine occurring for no apparent reason while suddenly feeling the need or urge to urinate. The most common cause of urge incontinence are involuntary and inappropriate detrusor muscle contractions.
– Functional incontinence – occurs when a person does not recognise the need to go to the toilet, recognise where the toilet is or get to the toilet in time. The urine loss may be large. Causes of functional incontinence include confusion, dementia, poor eyesight, poor mobility, poor dexterity or unwillingness. t
– Overflow incontinence – sometimes people find that they cannot stop their bladders from constantly dribbling or continuing to dribble for some time after they have passed urine.

Proctalgia fugax (PF) is a benign painful rectal condition that is defined as intermittent, recurring, and self-limiting pain in the anorectal region in the absence of organic pathology. The pain of proctalgia fugax is sharp or gripping and severe. Similar to other urogenital focal pain syndromes, such as vulvodynia and proctodynia, the causes remain obscure. Stress and sitting for prolonged periods often increase the frequency and intensity of attacks of proctalgia fugax. Patients often feel an urge to defecate with the onset of the paroxysms of pain . Depression often accompanies the pain of proctalgia fugax but is not thought to be the primary cause. The symptoms of proctalgia fugax can be so severe as to limit the patient’s ability to perform activities of daily living. Reassurance has proven to help in many cases as the condition has been linked to stress.

This muscle arises from the medial two-thirds of the supraspinatus fossa and from the supraspinatus fascia. It is inserted into the highest impression on the greater tubercle of the humerus after passing over the upper part of the shoulder joint. It works with the deltoid to raise the arm from the side of the trunk and initiate abduction. It also assists in fixation of the head of the humerus in the glenoid cavity.

Ameloblastoma is a rare, benign or cancerous tumour of odontogenic epithelium (ameloblasts, or outside portion, of the teeth during development) much more commonly appearing in the lower jaw than the upper jaw.
Ameloblastomas can be found both in the maxilla and mandible. Although, 80% are situated in the mandible with the posterior ramus area being the most frequent site. The neoplasms are often associated with the presence of unerupted teeth, displacement of adjacent teeth and resorption of roots.

Symptoms include a slow-growing, painless swelling leading to facial deformity. As the swelling gets progressively larger it can impinge on other structures resulting in loose teeth and malocclusion. Bone can also be perforated leading to soft tissue involvement.

The lesion has a tendency to expand the bony cortices because of the slow growth rate of the lesion allows time for the periosteum to develop a thin shell of bone ahead of the expanding lesion. This shell of bone cracks when palpated. This phenomenon is referred to as Egg Shell Cracking or crepitus, an important diagnostic feature.

Maxillary ameloblastomas can be dangerous and even lethal. Due to thin bone and weak barriers, the neoplasm can extend into the sinonasal passages, pterygomaxillary fossa and eventually into the cranium and brain. Rare orbital invasion of the neoplasm has also been reported.

A small number of foreign body aspirations are incidentally found after chest radiography or bronchoscopic inspection. Patients may be asymptomatic or may be undergoing testing for other diagnoses. If present, physical findings may include stridor, fixed wheeze, localized wheeze, or diminished breath sounds. If obstruction is severe, cyanosis may occur. Signs of consolidation can accompany post obstructive pneumonia.

Bronchoscopy can be used diagnostically and therapeutically. Most aspirated foreign bodies are radiolucent. Radiologic procedures do not have extreme diagnostic accuracy, and aspiration events are not always detected. Rigid bronchoscopy usually requires heavy intravenous sedation or general anaesthesia. The rigid bronchoscope has important advantages over the flexible bronchoscope. The larger diameter of the rigid bronchoscope facilitates the passage of various grasping devices, including a flexible bronchoscope. A better chance of quick, successful extraction and better capabilities of suctioning clotted blood and thick secretions are offered by the rigid bronchoscope. The paediatric flexible bronchoscope lacks a hollow working channel through which instruments may be inserted or blood and secretions may be aspirated.
Unlike the flexible bronchoscope, the patient can be ventilated through the rigid scope; therefore, ventilation of the patient can be maintained. Rigid bronchoscopy is the procedure of choice for removing foreign bodies in children and in most adults. Success rates for extracting foreign bodies are reportedly more than 98%. Large solid and semisolid objects are best managed emergently in the operating room with a rigid bronchoscope and appropriate grasping instruments.

The Monteggia fracture refers to a dislocation of the proximal radio-ulnar joint (PRUJ) in association with a forearm fracture, most commonly a fracture of the ulna. Depending on the type of fracture and severity, they may experience elbow swelling, deformity, crepitus, and paraesthesia or numbness. Some patients may not have severe pain at rest, but elbow flexion and forearm rotation are limited and painful.
The dislocated radial head may be palpable in the anterior, posterior, or anterolateral position. In Bado type I and IV lesions, the radial head can be palpated in the antecubital fossa. The radial head can be palpated posteriorly in type II lesions and laterally in type III lesions.

Colles’ fractures have the following 3 features:
– Transverse fracture of the radius
– 1 inch proximal to the radio-carpal joint
– Dorsal displacement and angulation

Smith’s fracture (reverse Colles’ fracture)
– Volar angulation of distal radius fragment (Garden spade deformity)
– Caused by falling backwards onto the palm of an outstretched hand or falling with wrists flexed

Bennett’s fracture
– Intra-articular fracture of the first carpometacarpal joint
– Impact on flexed metacarpal, caused by fist fights
– X-ray: triangular fragment at ulnar base of metacarpal

Galeazzi fracture
– Radial shaft fracture with associated dislocation of the distal radioulnar joint

Pott’s fracture
– Bimalleolar ankle fracture
– Forced foot eversion

Barton’s fracture
– Distal radius fracture (Colles’/Smith’s) with associated radiocarpal dislocation
– Fall onto extended and pronated wrist
– Involvement of the joint is a defining feature

Discrete masses graded P3 or R3/M3 or U3 and above should be triple assessed using core biopsy rather than FNAC unless core biopsy is not feasible.
When cytology or biopsy has been reported as C1 or B1 it will require a further biopsy to delineate the pathology in most instances.
The exceptions are when the lesion is suspected to be a lipoma or hamartoma following imaging and discussion. Following triple assessment, if there is non-concordance by more than one grade then further biopsy and or investigations should be undertaken.
In this case, Excisional biopsy is the next required biopsy to delineate the pathology.

Lambert–Eaton myasthenic syndrome is a rare disorder of the neuromuscular junction. It can occur as a solitary diagnosis but it can also occur as a paraneoplastic syndrome associated with lung cancer, particularly small-cell histology. It can also be associated with other cancers such as lymphoma, non-Hodgkin’s lymphoma, T-cell leukaemia, non-small-cell lung cancer, prostate cancer and thymoma.

Lymphatic filariasis, commonly known as elephantiasis, is a painful and profoundly disfiguring disease. In communities where filariasis is transmitted, all ages are affected. While the infection may be acquired during childhood its visible manifestations may occur later in life, causing temporary or permanent disability. The disease is caused by three species of thread-like nematode worms, known as filariae – Wuchereria bancrofti, Brugia malayi and Brugia timori. Male worms are about 3–4 centimetres in length, and female worms 8–10 centimetres. The male and female worms together form “nests” in the human lymphatic system.

Filarial infection can cause a variety of clinical manifestations, including lymphoedema of the limbs, genital disease (hydrocele, chylocele, and swelling of the scrotum and penis) and recurrent acute attacks, which are extremely painful and are accompanied by fever. The vast majority of infected people are asymptomatic, but virtually all of them have subclinical lymphatic damage and as many as 40% have kidney damage, with proteinuria and haematuria.

The proximal tubule is the portion of the duct system of the nephron leading from Bowman’s capsule to the loop of Henlé. The most distinctive characteristic of the proximal tubule is its brush border (or ‘striated border’). The luminal surface of the epithelial cells of this segment of the nephron is covered with densely packed microvilli forming a border which greatly increases the luminal surface area of the cells, presumably facilitating their reabsorptive function. Glucose, amino acids, inorganic phosphate, and some other solutes are100% reabsorbed via secondary active transport through co-transporters driven by the sodium gradient out of the nephron.

The patient is in hypovolemic shock, he is transfused with blood to replace the volume lost. It is important not only to replace fluids but stop active bleeding in resuscitation. Fluid replacement will result in a decreased sympathetic discharge and adequate ventricular filling thus reducing total peripheral resistance and increasing cardiac output and cardiac filling pressures.

Characteristically, the brain will undergo liquefactive necrosis following ischaemic injury. This leaves a cystic space in that region which would show up on a CT scan. Atrophy would result in a generalized decrease in the brain size. Coagulative necrosis typically occurs in parenchymal organs e.g. the spleen or kidney which have a lower lipid content. Caseous necrosis is typical in granulomatous tuberculosis infection. Apoptosis will not form a cystic area as it is programmed cell death involving a individual cells. Gangrenous necrosis is characteristic of ischaemic injury of the lower limb and GI tract. Fibrinous necrosis results from necrotic damage to the blood vessels with the leaking of proteins into the vessel, appearing bright pink on H & E staining.

The sternal angle is an important part where the second costal cartilage attaches to the sternum. Finding the sternal angle will help in finding the second costal cartilage and intercostal space.

A hamartoma is a condition best described as tissue normally present in an area arranged haphazardly in an disorganized, abnormal fashion. They are never malignant and do not metastasis.
All the neoplastic, cancerous lesions comprise of a mixture of different cells that are not normal to that area.
Metaplasia is a change in the type of the epithelium.

The inferior rectal vein drains into the internal pudendal vein. In addition the external iliac vein is one of the two branches of the common iliac vein however the internal iliac vein and it’s tributaries (including the pudendal vein) are much more important in draining the pelvic structures.

Iron deficiency anaemia is the most common type of anaemia. It can occur due to deficiency of iron due to decreased intake or due to faulty absorption. An MCV less than 80 will indicated iron deficiency anaemia. On the smear the RBC will be microcytic hypochromic and will also show piokilocytosis. iron profiles tests are important to make a diagnosis. Clinically the patient will be pale and lethargic.

Calcium is the most abundant mineral in the human body. The average adult body contains in total approximately 1 kg of calcium of which 99% is in the skeleton in the form of calcium phosphate salts. The extracellular fluid (ECF) contains approximately 22 mmol, of which about 9 mmol is in the plasma. About 40% of total plasma Ca2+ is bound to proteins and not filtered at the glomerular basement membrane. Therefore, the estimated daily filtered load is 1.5 mmol/l × 160 l/day = 240 mmol/day. The exact amount of free versus total Ca2+ depends on the blood pH: free Ca2+ increases during acidosis and decreases during alkalosis.