Miksomalar en sik kalpte izlenir ancak, daha az oranda ciltalti, aponörotik doku, kemik, genitoüriner sistem ve deri gibi diger dokularda da görülebilir. Kalp disi yumusak dokulardan kökenli miksomalardan olan “çizgili kaslarin miksomasi” görece enderdir. Olgumuz, sag üst kolda zamanla olusan sislik ve hareket kisitliligi yakinmasiyla basvuran 59 yasinda kadin hastadir. Fizik muayenesinde deltoid kas bölgesinde siskinlik ve palpasyonda ele gelen yumusak kitle izlenmistir. Magnetik rezonans anjiografisinde deltoid kas içinde hiperintens, düzgün sinirli; içerisinde hipointens septalarin izlendigi kitle saptanmistir. Makroskopik incelemesinde, 5.5x4x3 cm ölçülerinde, çevresinde kirmizi kas seçilebilen yumusak doku parçasina kesit yapildiginda çevre kas dokusundan düzgün sinirla ayrilan 3.2x3x2.5 cm boyutlarda parlak beyaz renkte, jelatinöz alanlar içeren lezyon izlenmistir. Mikroskopik incelemede, tümörün genis mukoid alanlar içinde dar sitoplazmali, hiperkromatik piknotik görünümlü çekirdekleri bulunan hücreler ve az sayida histiyositi animsatan hücrelerden olustugu gözlenmistir. Ender olarak görülen, pek çok benign ve malign miksoid neoplazmdan histopatolojik olarak ayirt edilmesi bazen çok güç olabilen, yumusak dokunun ilginç benign tümörlerinden biri olan intramusküler miksoma olgusuna ait klinik, radyolojik, patolojik özellikler sunulmus ve literatür esliginde tartisilmistir

Myxomas are most commonly seen in heart. However, it may occur less frequently in other tissues such as subcutaneous and aponeurotic tissues, bone, genitourinary tract and skin. Extracardiac myxomas such as intramuscular myxomas are very rare. A 59 year old female patient complained of swelling and pain in the right upper extremity was admitted. On physical examination a palpable, soft mass was detected in the right deltoid muscle. On magnetic resonance angiography a hyper-intense, nodular, well circumscribed mass with hypointense septa was detected. The lesion was removed completely. On gross examination the specimen was measured 5.5x4x3 cm with surrounding striated muscle tissue. On cut section of the specimen a well circumscribed, gelatinous, glittering, white colored mass measuring 3.2x3x2.5 cm was found. On histological examination, the tumor was composed of small cells with scant cytoplasm and hyperchromatic, pycnotic nuclei and small number of histiocytic cells within wide myxoid areas. In this report a rare case of intramuscular myxoma which should be differentiated from many benign and malignant myxoid neoplasms of soft tissues was presented and discussed in clinical, radiological and pathological aspects