Slow Growing Carcinomas of Lungs.

 Slow growing carcinoma of lungs

 PKGhatak, MD

Carcinoma is a cancerous growth of the cell that lines the inside of the glands and ducts of glands, it also includes surface cells (epithelial cells) of internal organs like the liver and intestine. The cancerous growth of the connective tissues is called sarcoma and cancers of blood cells are known as Leukemia.

Slow growing carcinomas and potentially malignant carcinomas of lungs were previously grouped under Bronchial Adenoma. Now they are in a separate group.

List of slow growing carcinomas and tumors benign in appearance with a tendency of recurrence and distant metastases.

1. Carcinoid tumors.

2. Adenocystic carcinoma.

3. Mucoepidermoid carcinoma.

Carcinoids.

Carcinoids of the lungs are the major lung tumor of this group, accounts for 85 % of all cancers of the lungs when Small Cell Cancer (SCC) and Non-Small Cell Cancers (NSCC) of the lungs are not included.

Carcinoid tumors also grow in all parts of the gastrointestinal tract, pancreas, ovaries, testis, appendix, thymus gland, and Meckel's diverticulum. Carcinoid tumors develop from Kulchitsky's cells, otherwise called neuroendocrine cells. These cells closely resemble nerve cells but secrete a wide variety of hormones and polypeptides which produce many symptoms due to excess hormone like actions.

This discussion on the endocrine effects of carcinoids will be limited to bronchial carcinoids. 

Symptoms of bronchial carcinoids.

Centrally located tumors are located in the trachea and in equal frequency in the right and left main bronchi. Peripheral carcinoids are much less frequent, and patients are mostly asymptomatic; often detected on chest CT or plain X-ray, an incidental finding. Peripheral carcinoids also cause pneumonia. Because of delayed diagnosis, many peripheral carcinoids are cancerous at the time of biopsy.

The centrally located carcinoid usually is a single lesion. They produce hemoptysis, cough, and episodic wheezing. Under the bronchoscope, the carcinoid tumor appears as a small cherry red, very vascular mucosal tumor. Both sexes are equally affected, usually in people over 50 yrs. of age but all age groups are known to have carcinoids.

The tumor cells are small polyhedral cells arranged in sheets, ribbons, and alveolar or glandular architecture. The nucleus of cells is mostly regular but irregular nuclei and mitotic activities indicate malignancy.

The blood circulation of bronchi is systemic, secretion from carcinoid drains directly into the bronchial veins and bypasses the liver. As a result, even a small amount of hormones/ hormone like substances produced generate significant and persistent symptoms. Carcinoid tumors secrete mostly serotonin and to a lesser amount of histamine, kallikrein, prostaglandins, tachykinins, and various amounts of 40 other chemicals. 

Midgut carcinoids produce a large amount of GI secretory and motility polypeptides.

About 10 % of bronchial carcinoids produce carcinoid syndrome.

Carcinoid syndrome and carcinoid crisis.

Serotonin is 5 hydroxytryptophan (5TP).5TP is produced from an amino acid - tryptophan. Platelets sore serotonin.

Bronchial carcinoids produce intense flushing of the face, neck and upper torsos and become red and itchy. Watery eyes and runny nose develop. Salivation is increased. Wheezing, watery diarrhea, and marked hypotension develop. Carcinoid syndromes are periodic and unpredictable, they may last 2 mins to several minutes and are usually prolonged in bronchial carcinoids.

Carcinoid Crisis.

Symptoms of carcinoid crisis are basically the same but more severe and sustained. Usually, it leads to cardiovascular collapse and cardiac arrhythmias, and death.

Carcinoid crises are precipitated by general anesthesia, tumor manipulation, biopsy, and surgery.

Pellagra.

Niacin is also called vitamin B3, It is also derived from tryptophan. In carcinoids, most of the tryptophan is shunted away for serotonin production. Vitamin B3 deficiency leads to pellagra. The symptoms are known by 3Ds - dementia, dermatitis, and diarrhea.

Increased Fibrosis.

Thickening of the right sided heart valves, intraventricular septum leads to congestive heart failure. Retroperitoneal fibrosis, urethral obstruction, Pyronine's syndrome may develop.

Other Endocrine Manifestations of bronchial carcinoids.

Neurosecretory products of carcinoids are varied - some are Pituitary hormones like GI secretory and motility polypeptides.

Type I Kulchitsky's carcinoid cells produce mostly bronchial obstructive symptoms.

Type II Kulchitsky's cells produce serotonin and other vasoactive and secretory polypeptides. And responsible for Serotonin syndrome and serotonin crisis.

Type III Kulchitsky's cell carcinoids are large cell carcinoma of the lung and Type IV cells are small carcinoma of the lung (SCC).   Type III and IV cell tumors secrete hormones and hormone like products.

The effects of these hormones produce the following syndrome/ entities.

1. Cushing's syndrome from excess ACTH.

2. Hyperpigmentation from melanocytes stimulating hormone.

3. Acromegaly and gigantism from excess growth hormone.

4. Hypoglycemia from insulin like products.

5. Hyperglycemia, hypertension, osteoporosis, renal stones and various other conditions.

 Metastases.

Bronchial carcinoid metastasizes to hilar lymph nodes, bones, and occasionally to distant places via blood.

Adeno Cystic Carcinoma.

Adeno cystic carcinoma is also known as Cylindroma. The tumor arises from the mucus glands of the trachea and main bronchi. The tumor is invasive in nature, spread along the airway underneath the surface layer cells and invades the hilum. and blood vessels. The tumor cells are small pleomorphic, the cells are arranged like tubes. The surrounding stroma shows myxomatous changes. The symptom is hemoptysis. Other symptoms are wheezing and partial bronchial obstruction.

Mucoepidermoid carcinoma.

Mucoepidermoid carcinomas are rare carcinomas and arise from the mucus glands of the trachea and major bronchi. The tumor is a mixture of several cellular types - well differentiated mucus cells, sheets of squamous cells with varying degrees of keratinization, and cellular bridges. Tumors are well circumscribed but noncapsulated and usually project into the lumen of the trachea or bronchi.

Symptoms. Hemoptysis, cough, fever, chest pain.

The tumor is a slow growing and does not invade local issues. Mitotic figures are few.

Diagnosis and treatment of slow growing carcinoma.

Bronchoscopy and biopsy give the proper diagnosis. The choice of treatment is surgical. Various techniques of surgery and the amount of tissues removed depend on the extent of lesions and degree of malignancy. The prognosis is generally good.

For diagnosis and treatment of bronchial carcinoid -please see a previous blog.

https://humihealth.blogspot.com/2011/06/carcinoid-and-other-neuroendocrine.html

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