Pulmonary hypertension (PH or PHTN) is a condition of increased blood pressure in the arteries of the lungs. Symptoms include shortness of breath, fainting, tiredness, chest pain, swelling of the legs, and a fast heartbeat. The condition may make it difficult to exercise. Onset is typically gradual.A patient is deemed to have pulmonary hypertension if the pulmonary mean arterial pressure is greater than 25mmHg at rest, or greater than 30mmHg during exercise.The cause is often unknown. Risk factors include a family history, prior blood clots in the lungs, HIV/AIDS, sickle cell disease, cocaine use, chronic obstructive pulmonary disease, sleep apnea, living at high altitudes, and problems with the mitral valve. The underlying mechanism typically involves inflammation and subsequent remodeling of the arteries in the lungs. Diagnosis involves first ruling out other potential causes.There is currently no cure for pulmonary hypertension, although research on a cure is ongoing. Treatment depends on the type of disease. A number of supportive measures such as oxygen therapy, diuretics, and medications to inhibit blood clotting may be used. Medications specifically used to treat pulmonary hypertension include epoprostenol, treprostinil, iloprost, bosentan, ambrisentan, macitentan, and sildenafil. Lung transplantation may be an option in severe cases.The frequency of occurrence is estimated at 1,000 new cases per year in the United States. Females are more often affected than males. Onset is typically between 20 and 60 years of age. Pulmonary hypertension was identified by Ernst von Romberg in 1891.
Microscopic histopathological analyses of hematoxylin and eosin stained FHI tumor tissues consistently reveal three very different component zones in virtually all cases: 1) haphazardly arranged, intersecting bundles of bland fibroblast-like/myofibroblast-like cells; 2) mature adipose (i.e. fat) tissue; and 3) highly vascular, myxoid (i.e. connective tissue appearing more blue or purple than normal connective) nodules of primitive-appearing spindled-shaped to star-shaped cells. Chronic inflammatory cell (e.g. lymphocytes, macrophages, and plasma cells) aggregates are commonly present in these lesion. The relative proportion of fibroblast/myofibroblast, adipose tissue, and myxoid zones commonly vary from case to case.Earlier Immunohistochemical analyses of FHI tumor tissues in a small number of cases have given varying results. A more recent and larger study reported that 75% of tested cases showed variable expression of smooth muscle actin proteins by the cells located primarily in fibroblast/myofibroblast zones and occasionally by the cells located in myxoid zones; the S100 protein was expressed by the fat cells of the adipose tissue zone in all cases; CD34 protein was expressed by the cells in myxoid and fibroblast/myofibroblast zones in all cases; and cells expressing the desmin protein were not detected in any case. A smaller, more recent study also found that 8 of 13 FHI cases had tumor cells in the fibroblast/myofibrobalast zone that expressed smooth-muscle actin protein, 6 of 8 cases had tumor cells in the myxoid zone that expressed the CD34 protein, and 7 of 7 cases had tumor cells in the adipose tissue zone express the S100 protein.