A 20-year-old male patient with a palpable mass on the plantar aspect of the foot with mild tenderness was admitted to the hospital for further evaluation. He had no history of recent trauma or any systemic complaints.
Conventional radiographs of the foot showed no calcification within the soft tissues. No accompanying osseous changes were observed.
Ultrasonography (US) revealed a hypoechoic, well-defined multilobulated mass lesion. There was no vascularization within the lesion on Doppler US (Fig. 1).
Magnetic resonance imaging (MRI) confirmed the presence of a well-defined multilobulated mass within the subcutaneous fat at the plantar aspect of the foot, extending along the fascial planes among the flexor muscles. The lesion was slightly hyperintense when compared to muscle on T1W images and peripherally hyperintense on fat saturated T2W images (Fig. 2). Marked peripheral enhancement was observed following the administration of gadolinium (Fig. 3).
A wide excisional biopsy was performed.
IPEH is generally considered an unusual form of thrombus organisation with excessive papillary endothelial proliferation and frequently seen superficially in the head, neck, trunk and fingers. It has no age predisposition but a slight predominance in females. It represents approximately 2-4% of the vascular tumours of the skin and soft tissue. Surgical excision is the treatment of choice for both diagnostic and curative purposes. Recurrence is extremely rare if the lesion is completely excised [1, 2].
Histologically, three different types have been described. The primary or pure form accounts for 56% of cases and arises in a dilated vessel. The secondary or mixed form (40%) originates on a pre-existing vascular lesion such as a haemangioma, pyogenic granuloma or vascular malformation. The very uncommon third form (4%) is the extravascular form which presents clinically as a primary neoplasm and histologically may mimic angiosarcoma [3].
Except one case which is located very close to the mandibula [4], no accompanying osseous change was defined with IPEH [5, 6]. Internal calcification within the mass has been reported in the mixed form which originates on a haemangioma and calcifications may be considered as phleboliths.
Magnetic resonance imaging (MRI) is important for diagnosis and preoperative planning. There are only a few small case reports and series that describe the MR appearance of IPEH [2, 7, 8]. The signal intensity on conventional MR sequences depends on the age of the thrombosis. Therefore, the lesion is hyperintense to muscle in the acute and medium stage and demonstrates hypo- to isointense signal in the chronic stage on T1W images and hyperintense on T2W images in all stages [2]. There are several patterns such as diffuse or septal and peripheral enhancement on contrast-enhanced studies. Septal and peripheral enhancement pattern seems to be the more frequent type which is consistent with the histopathological appearance defined as central thrombi with peripheral endothelial proliferation [2, 7, 8].
Ultrasound (US) findings of IPEH were reported to be nonspesific especially in the pure form. The lesion is mostly homogeneously hypoechoic on gray scale US. Doppler US may demonstrate septal or peripheral vascularities, reflecting the findings on MRI [8, 9].
In conclusion, IPEH is a rare vascular soft tissue tumour which shows endothelial proliferation with thrombus formation arising in a dilated vessel. MRI signal intensity characteristics are related to the age of the thrombus occurring within the lesion. Peripheral enhancement pattern is the most frequent type among a few cases reported in the literature, likewise in our case. US findings described in this case are nonspecific as hypoechoic and homogeneous on gray-scale US without internal vascularity on Doppler US. IPEH should exist in the differential diagnosis of a soft tissue tumour with peripheral or septal enhancement.
Intravasvular papillary endothelial hyperplasia
1. Ultrasound (US) findings: An oval-shaped, hypoechoic soft tissue mass is observed on the plantar aspect of the foot, with relatively clear boundaries to the surrounding tissue. In grayscale mode, the lesion appears uniformly hypoechoic. Doppler flow signals may show peripheral or septal distribution, but in this case, Doppler signals are limited (as shown in the image).
2. Magnetic Resonance Imaging (MRI) findings: The lesion is located in the soft tissue of the plantar foot. On T1-weighted imaging (T1W), it shows low to intermediate signal intensity, and on T2-weighted imaging (T2W), it shows high signal intensity. Contrast-enhanced scans indicate peripheral or septal enhancement. No obvious osseous destruction or periosteal reaction is noted. The lesion is relatively well-demarcated from surrounding fatty tissue, and there is no clear invasion of adjacent tendons or bone structures.
Based on the clinical presentation of only a plantar mass with mild tenderness, and imaging findings showing a hypoechoic lesion (US) with high signal on T2 (MRI) and peripheral enhancement, combined with literature descriptions of thrombus- and endothelium-related lesions, the following differential diagnoses can be considered:
Considering the patient's profile (young male), palpable plantar mass with mild tenderness, ultrasound and MRI findings, and the typical pathological features of thrombus formation and endothelial proliferation, the most likely diagnosis is:
Intravascular (within the vascular lumen) Papillary Endothelial Hyperplasia (IPEH)
If further confirmation is required, complete surgical excision of the mass followed by pathological and immunohistochemical examinations can be performed to confirm the diagnosis and rule out other vascular or soft tissue malignancies.
1. Treatment Strategy:
● As IPEH is generally a benign lesion, surgical excision is both diagnostic and curative.
● Surgical approach involves complete excision of the suspicious lesion while preserving critical plantar structures and performing necessary repairs.
● Postoperative recurrence rate is very low, and prognosis is favorable if the lesion is completely removed.
2. Rehabilitation and Exercise Prescription:
● Early phase (1–2 weeks): Emphasize protective weight-bearing, gentle foot joint movements to promote local circulation, and avoid excessive stretching or strenuous activities.
● Mid-phase (2–6 weeks): Based on the surgical incision and healing progress, gradually increase lower limb weight-bearing, and slowly introduce mild plantar strength training, such as seated foot exercises and ankle dorsiflexion and plantarflexion. Progress from partial to full weight-bearing.
● Late phase (after 6 weeks): Once normal gait is restored, strengthen the plantar muscles and improve proprioception through exercises like toe-standing and single-leg balance training to gradually restore foot function and stability.
● FITT-VP Principle:
• Frequency: 3–5 times per week, depending on individual recovery.
• Intensity: Start with low intensity and gradually increase; monitor foot fatigue or pain.
• Time: Each session can last 20–30 minutes, and duration can be increased progressively.
• Type: Begin with simple ankle movements, swimming, or cycling (low-impact exercises), and slowly increase the load.
• Progression: As pain and swelling subside, gradually increase weight-bearing and exercise difficulty.
● Emphasize foot protection: Use comfortable insoles, avoid prolonged standing or high-impact loading, and reduce exercise volume or seek medical evaluation if significant pain is experienced.
This report is based on the currently provided case information and imaging results, and is intended for reference only. It cannot replace in-person consultation or the opinion of a professional physician. Specific diagnosis and treatment plans should be determined by professional medical institutions and physicians based on a comprehensive clinical evaluation.
Intravasvular papillary endothelial hyperplasia
