Cystosarcoma phyllodes: epidemiology, pathohistology, pathobiology, diagnosis, therapy, and survival.

Cystosarcoma phyllodes is a very rare tumor which maybe difficult to diagnose clinically. The epidemiology and pathobiology are different from those of breast carcinoma. Risk factors, multicentricity, bilaterality, as associated with breast carcinoma, are not observed in patients with cystosarcoma phyllodes. Although the term "sarcoma" indicates a malignant tumor, only 10%-30% of cystosarcomas are histologically diagnosed as malignant; clinical diagnosis of malignancy does not exceed 10%. Axillary node involvement is rare, but hematogenous spread of cystosarcoma occurs into lung, pleura, bone, and liver. Clinically, cystosarcoma is a large (usually 3-5 cm in diameter) painless tumor with sudden growth acceleration especially during pregnancy. Cystosarcoma is usually circumscribed, containing firm and soft areas. The differential diagnosis has to include fibroadenoma, fibrocystic disease, mastitis, abscess, and medullary carcinoma. Neither clinical, mammographic or sonographic signs exist to predict a benign or malignant tumor. Therapy of cystosarcoma is not uniformly agreed upon. Radical, modified-radical, and simple mastectomy and tumorectomy are typical treatments; therapeutic results are the same for each treatment modality. For histologically diagnosed malignant cystosarcoma, the relative 5-year survival rate is about 80%. Clinically, malignant metastatic cystosarcoma is incurable; radiotherapy, endocrine treatment, and polychemotherapy are all ineffective. Because of the specific tumor pathobiology of cystosarcoma and its rarity, evaluation of treatment modalities and comparison of survival rates are difficult.