Ultrasound findings in subcutaneous plantar vein thrombosis: retrospective analysis of seven patients

Background Several disorders may result in forefoot pain. An uncommon cause of forefoot pain is subcutaneous plantar veins thrombosis (SCPVT) involving veins superficial to the plantar fascia. Purpose To describe the ultrasound (US) appearance of SCPVT, which has been described only once in the radiological literature. Material and Methods We performed a retrospective search of our PACS system from 2016 to 2020 to collect all cases of US-diagnosed SCPVT. We collected data on seven patients. Two radiologists analyzed the US images retrieved. All US examinations were performed with a multifrequency linear probe (frequencies in the range of 5-17 MHz). Results A localized plantar nodule was palpable in 86% of patients. The subcutaneous thrombosed vein appeared in all patients as a round or ovoid nodule located in the subcutaneous tissues that corresponded in four patients (4/5, 80%) to the painful palpable nodule. The size was in the range of 4-7 mm (mean = 5.4 mm). The thrombosed vein presented a connection with adjacent patent veins, appeared enlarged, and almost filled with hypo-isoechoic material, and in two patients (2/7, 29%), a thin peripheral fluid component surrounding the thrombus was detectable. Continuous scanning demonstrated slow blood movements inside the peripheral component due to blood circulation. Failure to compress the lumen of the thrombosed vein during the real-time US was evident in all patients. Conclusion SCPVT is a rare or underreported condition. Sonologists must know the US appearance of SCPVT to exclude other conditions and avoid unnecessary invasive studies.