Pulmonary metastasis is seen in 20-54% of extrathoracic malignancies. The lungs are the second most frequent site of metastases from extrathoracic malignancies. Twenty percent of metastatic disease is isolated to the lungs. The development of pulmonary metastases in patients with known malignancies indicates disseminated disease and places the patient in stage IV in TNM (tumour, node, metastasis) staging systems.
Chest radiography (CXR) is the initial imaging modality used in the detection of suspected pulmonary metastasis in patients with known malignancies. Chest CT scanning without contrast is more sensitive than CXR.
Breast, colorectal, lung, kidney, head and neck, and uterus cancers are the most common primary tumours with lung metastasis at autopsy. Choriocarcinoma, osteosarcoma, testicular tumours, malignant melanoma, Ewing sarcoma, and thyroid cancer frequently metastasize to lung, but the frequency of these tumours is low.

High-resolution CT (HRCT) scanning is more sensitive than standard chest radiography and is highly specific for diagnosing emphysema (outlined bullae are not always visible on a radiograph).

HRCT scanning may provide an adjunct means of diagnosing various forms of COPD (i.e., lower lobe disease may suggest AAT deficiency) and may help the clinician to determine whether surgical intervention would benefit the patient.

The combination of haemoptysis, chronic productive cough, and recent weight loss in a smoker is a strong indication of bronchogenic carcinoma.

Post-primary pulmonary tuberculosis is a chronic disease commonly caused by either endogenous reactivation of a latent infection or exogenous re-infection by Mycobacterium tuberculosis.
Post-primary pulmonary tuberculosis (also called reactivation tuberculosis) develops in 5%-20% of patients infected with M. tuberculosis.

Found mainly in adults, this form of tuberculosis arises from the reactivation of bacilli that lay dormant within a fibrotic area of the lung. In adults, reinfection with a strain of mycobacterium that differs from that which caused the primary infection is also possible. Predisposing factors include immunosuppression, diabetes, malnutrition and alcoholism.

Infliximab is a monoclonal antibody against tumour necrosis factor ? (TNF-?). It is FDA approved for many autoimmune conditions, including rheumatoid arthritis and Crohn’s disease. One of the many known side effects of infliximab therapy is reactivation of latent tuberculosis (TB). Because of the resemblances in clinical and radiological features, tubercular lesions in the lung may mimic malignancy. TB accounts for 27% of all infections initially presumed to be lung cancer on imaging studies.

Carbon monoxide (CO) is a colourless, odourless gas produced by incomplete combustion of carbonaceous material. Clinical presentation in patients with CO poisoning ranges from headache and dizziness to coma and death. Hyperbaric oxygen therapy can significantly reduce the morbidity of CO poisoning, but a portion of survivors still suffer significant long-term neurologic and affective sequelae.

Complaints:
Malaise, flulike symptoms, fatigue
Dyspnoea on exertion
Chest pain, palpitations
Lethargy
Confusion
Depression
Impulsiveness
Distractibility
Hallucination, confabulation
Agitation
Nausea, vomiting, diarrhoea
Abdominal pain
Headache, drowsiness
Dizziness, weakness, confusion
Visual disturbance, syncope, seizure
Faecal and urinary incontinence
Memory and gait disturbances
Bizarre neurologic symptoms, coma

Vital signs may include the following:
Tachycardia
Hypertension or hypotension
Hyperthermia
Marked tachypnoea (rare; severe intoxication often associated with mild or no tachypnoea)
Although so-called cherry-red skin has traditionally been considered a sign of CO poisoning, it is in fact rare.

The clinical diagnosis of acute carbon monoxide (CO) poisoning should be confirmed by demonstrating an elevated level of carboxyhaemoglobin (HbCO). Either arterial or venous blood can be used for testing. Analysis of HbCO requires direct spectrophotometric measurement in specific blood gas analysers. Elevated CO levels of at least 3-4% in non-smokers and at least 10% in smokers are significant.

Serial Peak Expiratory Flow measurement at work and home is a feasible, sensitive, and specific test for the diagnosis of occupational asthma. For a diagnosis of occupational asthma, it is important to establish a relationship objectively between the workplace exposure and asthma symptoms and signs. Physiologically, this can be achieved by monitoring airflow limitation in relation to occupational exposure(s). If there is an effect of a specific workplace exposure, airflow limitation should be more prominent on work days compared with days away from work (or days away from the causative agent). Airflow limitation can be measured by spirometry, with peak expiratory flow (PEF) and/or forced expiratory volume in 1 s(FEV1) being the most useful for observing changes in airway calibre. Other tests mentioned are less reliable and would not help in establishing a satisfactory diagnosis of occupational asthma.

In adult practice, biochemical analysis of pleural fluid plays an important part in the management of pleural effusions. Protein levels or Light’s criteria differentiate exudates from transudates, while infection is indicated by pleural acidosis associated with raised LDH and low glucose levels. In terms of treatment, the pH may even guide the need for tube drainage, suggested by pH <7.2 in an infected effusion, although the absolute protein values are of no value in determining the likelihood of spontaneous resolution or chest drain requirements. pH is therefore the most important factor.

CURB Pneumonia Severity Score:
– Confusion (abbreviated Mental Test Score <=8) (1 point)
– Urea (BUN > 19 mg/dL or 7 mmol/L) (1 point)
– Respiratory Rate > 30 per minute (1 point)
– Blood Pressure: diastolic < 60 or systolic < 90 mmHg (1 point) Based on the CURB Pneumonia Severity Score, the patient has severe pneumonia. According to the 2009 Centres for Medicare and Medicaid Services (CMS) and Joint Commission consensus guidelines, inpatient treatment of pneumonia should be given within four hours of hospital admission (or in the emergency department if this is where the patient initially presented) and should consist of the following antibiotic regimens, which are also in accordance with IDSA/ATS guidelines. For non-intensive care unit (ICU) patients:
Beta-lactam (intravenous [IV] or intramuscular [IM] administration) plus macrolide (IV or oral [PO])
Beta-lactam (IV or IM) plus doxycycline (IV or PO)
Antipneumococcal quinolone monotherapy (IV or IM)

If the patient is younger than 65 years with no risk factors for drug-resistant organisms, administer macrolide monotherapy (IV or PO)

For ICU patients:
IV beta-lactam plus IV macrolide
IV beta-lactam plus IV antipneumococcal quinolone

If the patient has a documented beta-lactam allergy, administer IV antipneumococcal quinolone plus IV aztreonam.

The most suitable antibiotic therapy for this patient is therefore Intravenous co-amoxiclav + clarithromycin.

Small cell lung cancer (SCLC) is characterized by rapid growth and early dissemination. Prompt initiation of treatment is important.

Patients with clinical stage Ia (T1N0) after standard staging evaluation may be considered for surgical resection, but combined treatment with chemotherapy and radiation therapy is the standard of care. Radiation therapy is often added at the second cycle of chemotherapy.

Historically, patients undergoing surgery for small cell lung cancer (SCLC) had a dismal prognosis. However, more recent data suggest that patients with true stage I SCLC may benefit from surgical resection.

Common sites of hematogenous metastases include the brain, bones, liver, adrenal glands, and bone marrow. The symptoms depend upon the site of spread.

The patient’s age, a history of long-term smoking, and bilateral hilar lymphadenopathy are strong indications of malignancy. Lymph node biopsy would be essential in order to check the degree of metastasis in the mediastinal lymph nodes.