Intravascular Papillary Endothelial Hyperplasia (Masson Tumor) of the Right Thumb: A Case Report and Literature Review

Summary:

The Masson tumor is a benign vascular tumor named after Pierre Masson, the French pathologist who originally described it in 1923, terming it “hémangio-endothéliome végétant intravasculaire.” It is a rare tumor that can arise in any area throughout the body. However, the exact cause of Masson tumor remains poorly understood, and its diagnosis is challenging and difficult to distinguish from several other soft-tissue tumors. In this report, we report a case of Masson tumor arising in the right thumb that is only the second reported case in the hand in Saudi Arabia.

INTRODUCTION

The Masson tumor is named after Pierre Masson, the French pathologist who described it in 1923 as a neoplastic lesion found in an ulcerated hemorrhoidal vein lumen.¹ It can arise in any area throughout the body with a tendency to occur in the head, neck, and extremities.^2–4 In 1932, Henschen postulated that the Masson tumor is a reactive process and not a neoplastic one.^5,6

In 1976, Clearkin and Enzinger challenged Masson’s theory. They believed that intraluminal thrombosis leads to papillary endothelial hyperplasia, and they gave it the more descriptive term intravascular papillary endothelial hyperplasia (IPEH).^7,8 Masson tumor diagnosis is challenging, as it is difficult to distinguish from other soft-tissue tumors and is an extremely rare tumor.^2,4,7 A Masson tumor was reported in Saudi Arabia for the first time in 2020; a 17-year-old woman presented a Masson tumor in the left metacarpophalangeal joint of the ring finger, which was managed by local excision and had no recurrence on the 1 year follow-up.⁹ In the current article, we report a case of Masson tumor arising in the right thumb that, to the best of our knowledge, is only the second case of Masson tumor or IPEH in the hand reported in Saudi Arabia.

CASE

A right-handed, 69-year-old female patient with a known case of controlled hypertension presented to the hand clinic with a mass on the dorsal surface of the right thumb, constant in size for 1 year and associated with mild pain. On examination, a round, nontender mass was observed occupying the dorsal side of the right thumb over the metacarpophalangeal joint level, measuring 1 cm × 1 cm, soft in consistency, and with normal overlying skin. Hand and thumb neurovascular examination and X-ray were unremarkable (Fig. 1).

Fig. 1.

X-ray images of the bilateral hands.

The duplex ultrasound study was performed for further investigation and showed a well-defined subcutaneous soft-tissue mass measuring 1.2 × 1.1 × 0.3 cm. It demonstrated few foci of internal vascularity and an absent area of vascularity with an area of small vascular pedicle connecting the lesion. The ultrasonographic features were compatible with those of thrombosed hemangioma (Fig. 2).

Fig. 2.

An ultrasound image of the tumor.

The patient underwent an excisional biopsy using a lazy-S incision over the mass (Fig. 3). Intraoperative findings were two feeding vessels located proximal and distal to the lesion which were ligated before excision, and the mass was not infiltrating any adjacent structures. No perioperative complications were encountered. The specimen was sent to a histopathology laboratory for a definitive diagnosis which was consistent with IPEH (Fig. 4).

Fig. 3.

The mass after the incision and dissection of skin flaps.

Fig. 4.

Endothelial proliferation in papillary architecture with hyalinized cores. Thrombus formation is also seen.

DISCUSSION

In the literature, IPEH constitutes around 2%–4% of reported skin and soft-tissue vascular tumors.^2–4,7 Furthermore, it tends to be more common in women, and it is hypothesized that IPEH expresses estrogen and progesterone receptors.^10,11 It tends to occurs in the third and fourth decades of life.^2,12 The exact cause of Masson tumor is still not well understood.^13,14 Several factors can play a role, but the most proposed cause is a preceding trauma, although around 70% of reported cases are idiopathic in nature.¹⁵

Trauma causes hematoma, with thrombosis and subsequent organization of the thrombus and the circulating macrophages producing growth factors that stimulate the proliferation of the endothelial layer of the blood vessels.^13,14 Other possible precipitating factors include vascular tumors, malformation, or pyogenic granuloma.¹⁴ IPEH has three subtypes histologically: primary intravascular subtype, which is the most common; secondary subtype, arising in a preexisting vascular lesion; and an extravascular type, which is the least common.^10,12,13

IPEH usually presents clinically as a well-circumscribed nonpulsatile mass arising from the skin and subcutaneous soft tissues. If the tumor is located superficially, the overlying skin may appear as blue or red with a slow growth pattern. It is firm in consistency, frequently small in size, and not adherent to or invading of adjacent structures.^2,3,9,15,16

In addition to the patient’s history and physical examination, preoperative imaging studies such as ultrasound, computed tomography, and magnetic resonance imaging are not that useful in differentiating IPEH from other vascular lesions,^13,16–18 as it appears as echogenic or hyperechogenic on ultrasound, which are contradictory findings.^7,19 On Doppler ultrasound, it appears as a hypervascular lesion, whereas on computed tomography and magnetic resonance imaging, it appears as a contrast enhancing homogeneous mass.^7,10 Owing to a lack of consistent and specific radiological findings, microscopic histological diagnosis remains the standard method for diagnosing IPEH.^2,13,18

However, it can be challenging, as IPEH closely resembles angiosarcoma. On a histological level, IPEH can be distinguished from angiosarcoma by its intravascular location, papillary proliferation of the endothelium with organized thrombosis, absence of tumor necrosis and cellular pleomorphism, and lack of mitotic activity. Conversely, angiosarcoma is characterized by increased mitotic activity, endothelial pleomorphism, invasion of surrounding tissues, and piling of endothelial cells. Furthermore, it is rarely found in the vessel lumen.^4,13,20

Immunohistochemistry can be implemented; IPEH is usually Glut1 negative, and WT1, CD31, CD34, ASMA, and factor VIII are positive. The CD105 marker is positive only in true primary vascular tumors, distinguishing IPEH from other similar vascular lesions, such as angiosarcoma.^{7,9,10,13,16,20}

IPEH is managed by simple excision, which is the gold standard treatment described in the literature.^{2,4,7,9,10,16} However, there is no consensus regarding whether margin resection is indicated.^9,16 It is curative with excellent prognosis, but a tumor recurrence rate of 15% has been reported that can be attributable to incomplete resection or preexisting vascular lesions.^2,4,7,9,16 However, there are no structured guidelines regarding the follow up period.² In the literature, adjuvant therapies such as radiotherapy and chemotherapy have been used for recurrent tumors but without clear indications.^7,9 Malignant degeneration has not been reported.¹⁶

CONCLUSIONS

IPEH is a benign vascular tumor accounting for 2%–4% of all skin and soft-tissue tumors. It shows a propensity toward the extremities and should be taken into consideration as a differential diagnosis of any hand mass. It is crucial to diagnose it accurately, as it can resemble angiosarcoma on histopathology. The gold standard treatment is local resection.

DISCLOSURE

The authors have no financial interest to declare in relation to the content of this article.