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

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

REVIEWED BY | Michelle Fenech ASA SIG: Musculoskeletal

REFERENCE | Authors: Bortolotto C, Draghi F, Bianchi S Journal: Acta Radiologica 2022; 63(11):1522–1527

WHY THE STUDY WAS PERFORMED

Subcutaneous plantar vein thrombosis (SCPVT) is an uncommon cause of forefoot pain. It involves thrombosis of the veins which sit superficial to the plantar fascia. Although deep plantar vein thrombosis is a recognised entity, SCPVT is less well appreciated, and prior to this study, SCPVT has previously been reported once before in radiologic literature. This study was performed to review cases in which SCPVT was sonographically identified and reported to enhance sonographic knowledge regarding this condition.

HOW THE STUDY WAS PERFORMED

A retrospective search of studies performed where SCPVT had been sonographically diagnosed between January 2016 to 2020 was undertaken. Seven positive cases were identified (3 men, 4 women; 47–61 years of age). Sonographic B-mode and colour and power Doppler imaging demonstrating SCPVT was retrieved and reviewed, as well as the clinical symptoms of presenting patients. The sonographic technique, B-mode (location, echogenicity, margins, shape, change with compression) and colour and power Doppler features of SCPVT and adjacent veins (to describe if they appeared within normal limits, dilated, or compressed) were documented.

WHAT THE STUDY FOUND

A localised painful plantar nodule was palpable at physical examination in 5 of 7 patients who presented for imaging. In patients without a plantar nodule, diffuse pain of the plantar aspect of the foot was reported. No skin changes were identified on any patients. The subcutaneous thrombosed vein appeared as a rounded or oval-shaped nodule in the subcutaneous plantar tissues ranging from 4–7 mm in size, which was connected to adjacent patent veins. Light and adjustable transducer pressure was required to demonstrate the superficial plantar veins. Thrombosed veins failed to compress completely during real-time scanning. Adjacent plantar foot structures were within normal limits in 5/7 patients, while one patient demonstrated concurrent plantar fasciitis and another patient demonstrated a small third intermetatarsal space Morton’s neuroma.

“Although reported as a rare entity, it may be underreported, and should be considered as a differential diagnosis to avoid invasive studies or surgical exploration.”

STRENGTHS AND LIMITATIONS OF THE STUDY

A retrospective analysis was conducted and ultrasound only was used as the imaging modality to confirm the diagnosis of SCPVT. Although the sample size reviewed for this report is small, this is expected in a rare entity. All patients were followed up and made a complete recovery.

RELEVANCE TO CLINICAL PRACTICE

This work highlights the importance of considering SCPVT as a condition that may be encountered sonographically when patients present with nodules and pain in the plantar aspect of the foot. Although reported as a rare entity, it may be underreported and should be considered as a differential diagnosis to avoid invasive studies or surgical exploration. Other causes of plantar nodules can include, most commonly, Ledderhose disease (plantar fibromatosis), which is a benign nodular thickening (may be singular or multiple) of the plantar fascia/aponeurosis, which does not usually demonstrate any vascularity inside the lesion on colour/power Doppler. Other conditions which may result in plantar nodules include plantar fascia tears, leiomyoma, schwannoma, warts, infected cysts and other less frequently encountered conditions (xanthoma, foreign body reactions, diabetic fascial disease, and local infections). These other conditions do not demonstrate any relationship with the superficial plantar veins. If SCPVT is identified sonographically, concurrent conditions of the plantar aspect of the foot still need to be excluded including Morton’s neuroma, intermetatarsal bursitis, adventitial bursitis, plantar plate tears, and metatarsophalangeal synovitis.