Mondor's Disease, also known as iron wire phlebitis, is a rare and self-limiting superficialvein thrombophlebitis that presents with a palpable cord-like induration beneath the skin. Otherssymptoms include: pain, swelling and redness of the affected area. It typically affects the vessels ofthe chest wall, less frequently the vessels of the penis or the upper limbs. The etiology of the diseaseis not fully understood, but it is known that it may be caused by local injuries or surgeries, and itmay accompany cancer or infections. The diagnosis is based in most cases on an anamnesis andphysical examination, confirmed by ultrasound. There are approximately 500 cases of this diseasedescribed in the literature. Iron wire phlebitis is a disease of underappreciated importance, raisingawareness of this condition can facilitate the MD’ diagnosis and reduce unnecessary diagnosticprocedures.A 36-year-old female patient detects a lump during breast self-examination. The lesion waslocated in the upper outer quadrant of the right breast. The ultrasound revealed dilated venousvessel with thrombosis, which led to diagnose Mondor's Disease. In this case the cause of increasedcoagulation may be ablation or COVID-19 infection. It is necessary to find the etiological factorspredisposing to the disease, and extending the diagnosis to exclude other rheumatological,hematological and neoplastic diseases. The patient received low-molecular-weight heparin, heparinointment, painkillers and anti-inflammatory drugs. After one week treatment, the change wasn’tpalpable. Then, instead of LMWH, oral sulodexide was used for treatment.Thanks to awareness of this disease, it was possible to made an appropriate, quicklydiagnosis and implement treatment, as well as reduce unnecessary medical procedures. The earlydiagnosis of MD can help to identify serious causes (for example breast cancer) at an early stagewhich will allow to treatment previously undetected changes.