Superficial Subungual Angiomyxoma: Case Report and Review of the Literature

To the Editor: Superficial angiomyxoma is a rare, cutaneous, acquired, benign, soft tissue neoplasm that can arise as a single tumor or multiple tumors. Histologically, it is characterized by the presence of a prominent vascular pattern and moderate inflammatory infiltrate within the myxoid matrix. Subungual location of angiomyxoma is very rare; to our knowledge, this is the fourth case. A 45-year-old male was referred in our department because of the appearance of clubbed nail deformity of the left thumb fingernail. The lesion had gradually increased in size during the last 5 months (Figure 1). The affected nail was slightly erythematous, sensitive when submerged in cold water, and occasionally painful; however, palpation did not produce any pain or fluctuant swelling. Additionally, the lesion did not limit the activity of the distal interphalangeal joint. No recent trauma of the affected fingernail was reported. According to the personal history, he used the computer daily. Radiographic examination of the digit demonstrated minimal soft tissue swelling that slightly elevated the nail plate. The tumor was removed 3 weeks after the initial examination in an outpatient setting. The lesion was oval with a myxoid texture, almost 2 cm in diameter. Histologic examination revealed a circumscribed lobulated mass with a prominent capillary network and spindleand stellateshaped cells (Figure 2). Immunohistochemical staining was positive for CD34 and negative for S-100. These findings were compatible with subungual angiomyxoma. Two months later, the surgical site healed, with an excellent cosmetic and functional result. No recurrence was seen at the 12-month follow-up visit. The bulbous digital deformity known as clubbing has been related to cardiac, pulmonary, and other systemic diseases. Isolated forms are due to local injury, whitlow, lymphangitis, or subungual neoplasms. The disorders that produce nail deformity may be malignant (melanoma, squamous cell carcinoma) or benign (mucous cyst, fibrokeratoma, exostosis, glomus tumor, keratoacanthoma, pyogenic granuloma, nerve sheath giant cell tumor). Cutaneous myxomas are well-demarcated nodules of the dermis or subcutis. Myxoma and superficial angiomyxoma are rare, benign, cutaneous neoplasms usually seen on the digits and also on the head, neck, trunk, and genital region. They are more sharply circumscribed and more vascular than cutaneous focal mucinosis. Histologically, these tumors express vimentin with variable positivity for CD34 and are usually negative for S-100 protein. Although the histologic features of superficial angiomyxoma are distinctive, its existence seems not to be widely accepted. Thus, some authors believe that ‘‘angiomyxoma’’ and ‘‘myxoma’’ are synonyms, whereas others consider superficial angiomyxoma to be a term used to describe cutaneous myxomas with more prominent vascularity. In 1988, Allen and colleagues presented 30 cases of superficial angiomyxoma and reported its differentiation from myxoma, based on the presence of collagenous diaphragms, rich vascularity, and inflammatory cell infiltrate in a mucoid matrix seen in angiomyxoma. Calonje and colleagues also supported the concept of superficial angiomyxoma as a distinct entity. Superficial angiomyxoma affects all ages, with a peak incidence in the third to fourth decade of life. Superficial angiomyxoma has been reported as a solitary lesion, usually less than 5 cm in diameter, or in association with Carney complex (skin and cardiac myxomas, spotty skin pigmentations, endocrine overactivity, and endocrine tumors), NAME syndrome (nevi, atrial myxoma, myxoid neurofibroma and ephelides), or LAMB syndrome (mucocutaneous lentigines, atrial myxomas, mucocutaneous myxomas, and blue nevi). Angiomyxomas in unusual positions, such as the floor of the mouth, eyelid, and epididymis, have also been described. Sanusi described a case of subungual myxoma in 1982. The first case of subungual superficial angiomyxoma was reported in 2002. Two cases of subungual angiomyxomas occurring on the thumb and the fifth toe were reported in 2005, and the fourth case is the present. Misago and colleagues also reported a fibrokeratoma-like lesion on the radial lateral side of the proximal interphalangeal joint of the right index finger. Clubbed nail deformity was the clinical presentation manifestation in all cases of subungual myxomas and angiomyxomas. Pain has rarely been reported in subungual myxoma, whereas a previous history of trauma of the fingernail was reported in one case of subungual myxoma. DOI 10.2310/7750.2011. 10036