Pericarditis classically manifests with atypical chest pain (not related to exertion and worse in recumbency), and a prominent friction rub. When associated with significant fluid accumulation, acute pericarditis can cause cardiac tamponade, which leads to declining cardiac output and consequent shock. Chronic constrictive pericarditis produces a combination of right-sided venous distention and low cardiac output, similar to the clinical picture in restrictive cardiomyopathy.
Primary cardiac tumors are uncommon; moreover, most also are (fortunately) benign. The five most common have no malignant potential and account for 80% to 90% of all primary heart tumors. In descending order of frequency, these are myxomas, fibromas, lipomas, papillary fibroelastomas, and rhabdomyomas. Angiosarcomas constitute the most common primary malignant tumor of the heart. Only the myxomas and rhabdomyomas merit further mention here.
Fig. 11.29 Acutesuppurative(purulent,exudative)pericarditis,causedbyextensionfromapneumonia.
Myxomas are the most common primary tumors of the adult heart (
Fig. 11.30 ). Roughly 90% are atrial, with the left atrium accounting for 80% of those.
Rhabdomyomas are the most frequent primary tumors of the heart in infants and children; they frequently are discovered owing to valvular or outflow obstruction. Cardiac rhabdomyomas occur with high frequency in patients with tuberous sclerosis caused by mutations in the TSC1 or TSC2 tumor suppressor genes; loss of TSC-1 and TSC-2 activity leads to myocyte overgrowth. Because they often regress spontaneously (for unknown reasons), rhabdomyomas are sometimes considered to be hamartomas rather than true neoplasms. In keeping with this not all cardiac rhabdomyomas that occur in patients with tuberous sclerosis are clonal.
MORPHOLOGYMyxomas arealmostalwayssingle,classicallyarisingintheregionofthefossaovalis(atrialseptum).Theycanbesmall(lessthan1cmindiameter)ormassive(upto10cmacross),sessileorpedunculatedmasses(
Fig.11.30A ),mostoftenmanifestingassoft,translucent,villouslesionswithagelatinousappearance.Pedunculatedformsoftenaresufficientlymobiletoswingintothemitralortricuspidvalveduringsystole,causingintermittentobstructionorexertinga“wreckingball”effectthatdamagesthevalveleaflets.
Histologically,myxomasarecomposedofstellate,frequentlymultinucleatedmyxomacells(typicallywithhyperchromaticnuclei),admixedwithcellsshowingendothelial,smoothmuscle,and/orfibroblasticdifferentiation;allofthecelltypesarisefromdifferentiationofmultipotentialmesenchymaltumorcells.Thecellsareembeddedinanabundantacidmucopolysaccharidegroundsubstance(
Fig.11.30B ).Hemorrhage,poorlyorganizingthrombus,andmononuclearinflammationalsoareusuallypresent.
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Fig. 11.30 Atrialmyxoma.(A)Alargepedunculatedlesionarisesfromtheregionofthefossaovalisandextendsintothemitralvalveorifice.(B)Abundantamorphousextracellularmatrixcontainsscatteredmultinucleatemyxomacells(arrowheads) invariousgroupings,includingabnormalvascularformations(arrow).