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Overview Histoplasmosis is an infection caused by breathing in spores of a fungus often found in bird and bat droppings. People usually get it from breathing in these spores when they become airborne during demolition or cleanup projects. Soil contaminated by bird or bat droppings also can spread histoplasmosis, putting …

What is Hydronephrosis? Hydronephrosis is the swelling of a kidney due to a build-up of urine. It happens when urine cannot drain out from the kidney to the bladder from a blockage or obstruction. Hydronephrosis can occur in one or both kidneys. The main function of the urinary tract is …

Overview Hiatus hernia is the term used to describe a condition where part of the stomach pushes up into the lower chest through a weakness in the diaphragm. The diaphragm is the large flat muscle that separates the lungs from the tummy (abdomen) and helps us to breathe. Not everyone …

Definition Hoarding disorder is an illness that makes people feel a very strong need to collect things. They can’t bear to think about parting with their things. Over time, the collected items may take over the person’s house. The items may cover tables, beds, counters, and floors. Hallways and rooms …

Definition Herpangina, mild viral infection caused by several enteroviruses, most of which are in the subgroup Coxsackie A, seen most commonly in young children. The most distinctive symptom is a rash on the mucous membranes inside the mouth. The lesions in the mouth are round macules (nonraised spots) about 2 …

Definition Hidradenitis suppurativa (HS) is a chronic skin disease which causes painful, boil-like lumps that form under the skin and often secrete pus and blood. HS occurs most often in areas where skin rubs together, such as the armpits, groin, and under the breasts. Symptoms usually begin after puberty. The …

What is Hematoma? Hematoma is generally defined as a collection of blood outside of blood vessels. Most commonly, hematomas are caused by an injury to the wall of a blood vessel, prompting blood to seep out of the blood vessel into the surrounding tissues. It can result from an injury …

Definition Heartburn is a sensation of burning in the chest caused by stomach acid backing up into the esophagus (food pipe). The burning is usually in the central part of the chest, just behind the sternum (breast bone). The burning can worsen or can be brought on by lying flat …