Microcitoma (Small Cell Lung Cancer)

3 DIAGNOSIS

3.1 Signs and symptoms

3.1.1 General data
Signs and symptoms depend on the location of the primary tumor and site of the metastatic lesions. More than 80% of SCLC-patients report symptoms for 3 months or less, and very few are asymptomatic at the time of diagnosis.

3.1.2 Signs and symptoms
SCLC usually presents as large, rapidly growing lesions arising from the centrally located tracheobronchial airways and invading the mediastinum. Typically, patients present cough (75% of patients) or dyspnea, wheezing, chest pain (20-35% of patients). The submucosal nature of SCLC accounts for the relative infrequency of hemoptysis (about 15%) as compared to squamous carcinoma. Weight loss, fatigue and anorexia occur in up to one-third of patients. SCLC is the most common type of lung cancer with signs and symptoms of mediastinal involvement, including superior vena cava syndrome, hoarseness or dysphagia.

3.1.3 Site of metastasis
At the time of diagnosis, two-thirds of the patients with SCLC have one or more clinically detectable distant metastasis, including bone (30%), liver (25%), bone marrow (20%) and central nervous system (10%).

3.1.4 Paraneoplastic syndromes
Several paraneoplastic syndromes appear to be specifically associated with SCLC, as the syndrome of inappropriate antidiuretic hormone secretion (11%), ectopic Cushing's syndrome (2.4%) and the Eaton-Lambert or myasthenia-like syndrome.

3.2 Diagnostic strategy

3.2.1 Diagnostic strategy
Physical examination and chest X-ray films are recommended. The chest X-ray usually shows a large-sized, centrally located, not cavitated mass associated with hilar and mediastinal adenopathies and signs of mediastinal invasion. In a screening setting, sensitivity of chest X-ray ranges from 45 to 50%, sputum cytology from 25 to 30% and their combination from 60 to 67%. This typically differs from what expected from non-small cell lung cancer patients. Due to their low sensibility and specificity, tumor markers, like neuron-specific enolase or creatine kinase BB or neuroendocrinological markers, are not useful in the diagnostic phase. They are elevated in 60-65% of cases at diagnosis and correlate to tumor bulk and to tumor response. They may be employed during treatment and follow-up, being predictive of disease progression 30-60 days before it becomes clinically evident. The usefulness of a relapse diagnosis anticipation is marginal since salvage treatments are virtually none.

3.3 Pathological diagnosis

3.3.1 Cytological and histological specimens
Bronchoscopy easily yields cytological and histological specimens in patients with centrally-located lesions in more than 90% of cases. To avoid unnecessary opening of the pleural cavity, the use of video-assisted thoracoscopic evaluation is not recommended. If not yielding a pathological diagnosis on primary tumor, other major invasive diagnostic techniques may include surgical biopsy of scalene or cervical nodes, cervical mediastinoscopy for patients with pretracheal and laterotracheal nodes or superior vena cava syndrome, mediastinotomy for lesions located at the left hilum associated with subaortic nodes or nodes of the anterior mediastinal chain. A fine-needle aspiration cytology may be helpful for peripherally located lesions. However, in a patient presenting with a solitary parenchymal nodule without mediastinal adenopathy and increasing in size over a short period of time, surgery may be considered recommended on a type R basis.

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