Painful Angiomyoma of the Heel Region: A Rare Case Report

Discussion

Most subcutaneous tumors in the foot and ankle are benign. The differential diagnosis includes giant cell tumor, angiomyoma, lipoma, epidermoid cyst and schwannoma, although angiomyomas are less commonly encountered. Angiomyomas, a subtype of leiomyomas (3), are benign smooth muscle tumors originating from the tunica media of blood vessel walls (4, 5). The peak incidence occurs between the fourth and sixth decade of life, with a predilection for the lower extremities, particularly in women (6), which is consistent with our case. Clinically, patients often present with pain, especially in weight-bearing areas such as the heel (3). The pain is thought arise from nerve compression or ischemia within the tumor. In our case, the patient’s only symptom was pain, without evidence of neurovascular involvement.

Due advancements in imaging modalities such as ultrasound and magnetic resonance imaging (MRI), diagnosing angiomyomas remains challenging due to their nonspecific clinical presentation. On MRI, angiomyomas typically appear as well-defined lesions surrounded by a thin hypointense capsule. They are homogeneous and isointense to skeletal muscle on T1-weighted sequences, while on T2-weighted and short tau inversion recovery sequences, they display heterogeneously increased signal intensity compared to skeletal muscle. Additionally, angiomyomas generally show strong enhancement following gadolinium contrast administration (7). However, these MRI characteristics are still relatively nonspecific, underscoring the need for histopathological confirmation.

In the presented case, only an ultrasound examination was performed. Ogata et al. suggested that a combination of thorough physical examination and ultrasonographic evaluation is typically sufficient to differentiate angiomyomas from schwannomas (8). Angiomyomas are generally smaller (<0.2 cm) and lack the entering or exiting nerve roots commonly observed in schwannomas. Key features such as tumor size, location, and the presence or absence of associated nerve roots can aid in distinguishing between these two entities. Szolomayer et al. reported eight cases of leiomyomas in the foot and ankle, with an average size of 3.85 cm-significantly larger than the 0.5 cm lesion observed in our case (7). The smaller size in our case increased the likelihood of misdiagnosis as another type of subcutaneous tumor. Surgical excision, combined with immunohistochemical staining, remains the gold standard for diagnosing these tumors. Positive immunohistochemical staining for SMA confirms the diagnosis of angiomyoma. Notably, a low recurrence rate has been reported following excision (9).

In conclusion, we present a case of angiomyoma in the heel region, highlighting its clinical presentation alongside radiographic and histological features. A combination of meticulous physical examination and ultrasonographic evaluation can aid in establishing the diagnosis. Clinicians should consider angiomyoma as a differential diagnosis for painful subcutaneous tumors in the foot and ankle, particularly in middle-aged female patients.