Intramuscular hemangioma is a rare, benign, soft-tissue tumor, constituting approximately 1% of all hemangiomas. These lesions predominantly arise on the extremities or trunk. Chest wall hemangiomas are extremely rare tumors that may originate within soft tissue or ribs.(1) Furthermore, to date, there are no available reports on the distant recurrence of intramuscular hemangioma, even though there have been a few reports of local recurrence. Previous studies reported that surgical margins and tumor infiltration into the muscle are associated with local recurrence.(2,3)

Due to the distant recurrence of intramuscular hemangioma, it is challenging to appropriately diagnose the distant recurrence of multiple intramuscular hemangioma s at unusual sites. Herein, we report the case of a 36-year-old woman with two intramuscular hemangiomas on the chest wall who had a personal history of undergoing complete surgical excision for an intramuscular hemangioma of the upper extremity ten years ago. Furthermore, this report emphasizes the importance of identifying the ultrasonographic features associated with the distant recurrence of multiple intramuscular hemangioma s at unusual sites.

A 37-year-old woman presented to our hospital with a fixed, firm, palpable, slowly growing, painless mass on the left forearm that she had noticed 2 years ago. The patient had no history of other malignancies or family history of breast cancer. Plain radiography revealed a large soft tissue mass containing phleboliths within the mass (Fig. 1A). Ultrasonography (US) of the upper extremity showed an approximately 1.3 × 3.0 cm indistinct, complex cystic solid mass in the left forearm (Fig. 1B) and a 1.2 × 3.0 cm solid mass with heterogeneous echogenicity in the distal palmar aspect of the left fourth finger. She underwent an excisional biopsy of the masses. Gross pathological examination revealed intermixed muscle and fat tissue and large blood vessels infiltrating the surrounding muscles. The mass was diagnosed as an intramuscular venous heman-gioma.

Ten years later, she was referred to our hospital because two masses were incidentally detected on breast US. Mammography did not reveal any significant findings. However, breast US showed an approximately 1.6 × 0.9 cm oval, circumscribed, hypoechoic mass and a 1.3 × 3.0 cm oval, circumscribed complex cystic and solid mass (Fig. 2). Ultrasonography revealed divergent pectoral muscle fibers at the periphery of these masses. The patient had previously undergone ultrasound-guided core biopsies for breast lesions; however, the pathological results were inconclusive and showed blood clots and inflamed fibromuscular tissue. Therefore, complete surgical excision of the masses within the pectoralis major muscle was performed, and pathological examination revealed large blood vessels infiltrating the surrounding muscle, vascular spaces lined with endothelial cells, and stroma consisting of fibrous connective tissue (Fig. 3). The histological diagnosis was an intramuscular cavernous hemangioma.

Intramuscular hemangioma is a rare vascular disease involving the skeletal muscles. It is characterized by the proliferation of endothelial cells originating from the vascular tissue of the mesoderm, with pathological changes becoming more pronounced after trauma. It exhibits infiltrative and invasive growth patterns without obvious capsules or boundaries. The etiology of intramuscular hemangiomas remains uncertain, with both congenital and posttraumatic theories being considered.(4) Traumatic and hormonal factors have been suggested to contribute to the etiology or growth spurts of tumors.(5) Intramuscular hemangiomas were classified by Enzinger and Allen based on the predominant vessel size: capillary (small vessel type), cavernous (medium-large vessel type), and mixed (consisting of both).(6) Intramuscular hemangiomas are rare, benign, soft-tissue tumors that account for approximately 1% of all hemangiomas. These tumors mostly occur in the extremities or trunk, while intramuscular haemangiomas of the breast account for only 0.4% of all breast tumors.(1,7) Typically, these vascular tumors are found within the breast tissue; however, they can also originate from the chest wall as intramuscular hemangiomas.

In the early stages, most patients with intramuscular hemangiomas exhibit no specific symptoms. In the later stages, symptoms may include myosclerosis, contracture, deformities, and muscle and joint dysfunction. Owing to its deep location, variable size and shape, lack of specific clinical symptoms, and absence of obvious biological characteristics, the preoperative diagnostic rate of intramuscular hemangioma is only 8-19%.(8) These rare vascular tumors are often not suspected based on clinical findings, making them a diagnostic challenge for clinicians.(9) In addition, given its rarity, the diagnosis of distant recurrent intramuscular hemangiomas of the breast is challenging. Plain radiographs may reveal nonspecific findings such as phleboliths and calcifications.(10) Moreover, focal calcification within the mass is frequently observed in other soft tissue tumors such as leiomyomas and epidermoid cysts. Although magnetic resonance imaging is the standard imaging modality for the diagnosis of intramuscular hemangiomas, its accessibility is limited. In contrast, the US has a higher accessibility.(10) US may depict ill-defined heterogeneous lesions that are predominantly isoechoic to the surrounding muscle tissue, combined with sluggish venous flow on color Doppler imaging, which aids in diagnosing intramuscular hemangiomas of the breast.(4) US has a high specificity for diagnosis, particularly for estimating the extent of tissue infiltration.

In conclusion, using US findings to detect ill-defined heterogeneous lesions in the vicinity of muscle tissue, which are readily accessible, can facilitate the early and accurate diagnosis of distant recurrence of intramuscular hemangiomas following complete surgical resection.

This paper was supported by Fund of Biomedical Rresearch Institute, Jeonbuk National University and Hospital.

There are no conflicts of interest.