GIANT MYXOMA,
SARCOMA
A variety of fibroadenoma growing to immense size and occurring near the menopause was first described by the distinguished physiologist of the early 19th century, Johannes Müller, as “cystosarcoma phyllodes.” This is a rare, predominantly benign tumor that occurs almost exclusively in the female breast. It represents less than 1% of all breast tumors. The duration of the growth extends over a period of 6 or 7 years, with rapid growth toward the end of this period, when these tumors can significantly increase in size in just a few weeks. The benign character of the growth is indicated by the absence of invasion of the skin or of the regional lymph nodes. The tumors are heavy, massive, lobulated growths with cystic areas. They have a sharply demarcated smooth texture and are typically freely movable. Their average weight is between 7 and 8 lb. In spite of the size, the tumor remains movable and encapsulated, and the nipple is not retracted. Grossly, the tumor displays characteristics of a large malignant sarcoma, takes on a leaf-like appearance when sectioned, and displays epithelial cystic spaces when viewed histologically. Because most of these tumors are benign, the name may be misleading, leading to the preferred terminology of phyllodes tumor or giant myxoma.
The origin of these growths is in a
preexisting intra-canalicular myxoma. Dense fibrous tissue in whorls is
separated by clefts from polypoid, fibrous, and epithelial masses projecting
into cystic cavities. Under the microscope, the predominant component is
myxomatous connective tissue with intervening dense fibrous strands. The
majority of the growths are benign, but some may be the seat of sarcomatous
change in about 10% of cases, particularly when the tumor has existed for many
years. These tumors are best treated by simple mastectomy with removal of the
pectoralis fascia. Although these benign tumors often do not metastasize, they
do have a reputation of growing aggressively and recurring locally. The
malignant tumors metastasize hematogenously like other sarcomas. The histologic
appearance does not always predict clinical behavior. Roughly 30% of patients
with malignant phyllodes tumors will die from their disease. Other than surgery,
there is no cure for phyllodes tumors, as chemotherapy and radiation therapy
are not effective. Current studies do not support the use of adjuvant
radiotherapy for patients with adequately resected disease.
Mammary sarcoma is relatively rare
and represents between 1% and 2% of breast
tumors. Many varieties of sarcomas, such as osteogenic, lympho-, myo-, lipo-,
and myelosarcomas, have been described. In more than half of the cases,
however, sarcomas of the mammary gland are of the fibrospindle cell–type arising
in the stroma of the breast or from the stroma of
preexisting fibroadenomas. The tumors, which may develop at any age but have
their peak incidence between 45 and 55 years of age, are characterized by rapid
growth, large size, and a firm consistency. Ulceration of the skin, with
fungation, may occur. The tremendous size and the absence of axillary node
involvement distinguish these growths from mammary carcinomas. Pain and rapid
growth are the symptoms most commonly noted. A preexisting fibroadenoma may have
been stationary and asymptomatic for many years
and then suddenly may become painful, giving rise to the rapidly growing and
invading sarcoma.
Sarcomatous change has also been
seen in benign myxomas. Grossly, the tumors are solid, fleshy growths, which may
invade the pectoralis fascia. Microscopically, they are composed of tightly
packed pleomorphic spindle cells. The treatment is radical mastectomy. The
lungs are the most common metastatic site, followed by bone, heart, and liver.
