| Japanese Journal of Clinical Oncology | Pages |
Introduction
Case Report
Pathological Findings
Macroscopic Findings
Microscopic Findings
Immunohistochemical Findings
Discussion
Acknowledgements
References
Superficial Angiomyxoma of the Right Inguinal Region: Report of a Case
We report one rare case of superficial angiomyxoma of the right inguinal region, in a 67-year-old man. The tumor, measuring 4.5*4.0*3.0 cm, had a finger-like shape, was composed of a well circumscribed conglomerate of multiple myxomatous nodules and was located partially in the dermis and partially in the subcutaneous tissue. Microscopically, in contrast to previously reported cases, the tumor was composed mainly of oval plump stromal cells with an amphophilic cytoplasm. Spindle-shaped stromal cells were scattered throughout the tumor. The tumor border was not infiltrative and was well defined by thick hyalized collagen bundles. Neither hyperchromasia nor pleomorphism was apparent. No mitotic figures were detected in the specimens prepared. Small to medium-sized blood vessels showed a scattered distribution, but large vessels, seen frequently in aggressive angiomyxoma, were absent. Moreover, no plexiform capillary pattern was evident. These findings were diagnostic of superficial angiomyxoma. Although this disease entity is considered as including cutaneous focal mucinosis, follicular fibroma, trichofolliculoma and trichogenic adnexal tumor, we propose that these tumors should be excluded.
INTRODUCTION
Superficial angiomyxoma is a rare benign neoplasm characterized by a conglomerate of multiple, moderately to sparsely cellular angiomyxoid nodules with scattered small to medium-sized blood vessels (1 ). In 1988, Allen et al. reported 30 superficial angiomyxomas in 28 patients, nine of which had epithelial elements (1 ). They used the word `superficial' in order to distinguish superficial angiomyxoma from aggressive angiomyxoma, which is an uncommon, locally aggressive but non-metastasizing soft tissue neoplasm occurring preferentially in the female genital region (2 -6 ). We present one case of superficial angiomyxoma in a 67-year-old man and discuss the morphological features, both macroscopic and microscopic, most helpful for distinguishing this tumor from other soft tissue tumors, especially cutaneous focal mucinosis, cutaneous myxoid cyst and aggressive angiomyxoma. We also discuss the disease entity `superficial angiomyxoma'.
The patient was a 67-year-old male. Since November 1995, he had been aware of a protruding tumor, measuring about 3 * 2 * 2 cm localized in the right inguinal region, associated with itching. Due to vigorious scratching, the tumor had grown larger. Surgical resection of the tumor was performed on April 19, 1996, and no recurrence had been detected at the time of writing, eight months later. The patient had no signs of cardiac myxoma.
Grossly, the tumor had a finger-like shape, measuring 4.5 * 4.0 * 3.0 cm, and its tip showed ulceration with hyperkeratosis of the adjacent epidermis (Fig. 1 ). The cut surface revealed that the tumor was located partially in the dermis and partially in the subcutaneous tissue, being circumscribed by a thick capsule. It included yellowish-white, lobulated nodules separated by incomplete septa (Fig. 1 ).
The tumor was well defined and characterized by thick collagen bundles (Fig. 2 ). It was separated into compartments by hyalinized collagenous septa. The density of stromal cells and collagen fibers varied among different areas. Some areas were relatively cellular with abundant collagen fibers and small vessels (Fig. 2 ), whereas others were characterized by a myxoid matrix admixed with collagen fibers forming clefts and mucin pools, and a moderate to sparse population of stromal cells (Fig. 2 ). In contrast to previously reported cases, most of the stromal cells were unipolar and oval-plump; they had an amphophilic cytoplasm and an oval nucleus with a few inconspicuous nucleoli (Fig. 2 ). A small number of spindle-shaped stromal cells were also seen. Neither hyperchromasia nor pleomorphism was apparent. No mitotic figures were detected in the specimens prepared. Small to medium sized blood vessels were scattered throughout both the cellular and myxoid areas (Fig. 2 ). A few lymphocytes had infiltrated around the blood vessels (Fig. 2 ). However, neither large-caliber vessels nor plexiform capillaries were apparent. Additional epithelial components were not seen.
Immunohistochemical studies were performed by means of the avidin-biotin complex technique (7 ). The antibodies used are listed in Table 1 . Vimentin was positive in the cytoplasm of the stromal cells (Fig. 3 ), but not S-100, alpha-smooth muscle actin, desmin or CD34.
In 1988, Allen et al. proposed the disease entity `superficial angiomyxoma', which was a benign myxomatous neoplasm characterized by moderately to sparsely cellular angiomyxoid nodules with scattered small vessels (1 ). Since then, two well-known textbooks of surgical pathology have described this entity (8 ,9 ). However, only one case has been reported as cutaneous angiomyxoma, almost synonymous with superficial angiomyxoma, occurring on the head of a 38-year-old man (10 ). Superficial angiomyxoma needs to be differentiated from other benign cutaneous myxomatous lesions (cutaneous focal mucinosis and cutaneous myxoid cysts) and borderline malignant myxomatous tumor (aggressive angiomyxoma).
Macroscopically, cutaneous focal mucinosis and cutaneous myxoid cysts are generally small, ill-defined nodular lesions <2 cm in diameter (11 ). Aggressive angiomyxomas are usually infiltrative (2 -6 ) and even if they show a relatively sharp margin, at least a small part of the growing edge displays entrapment of adipose tissue. In contrast, superficial angiomyxomas are generally larger than cutaneous focal mucinoses and cutaneous myxoid cysts, and are not infiltrative but well circumscribed (1 ,11 ). The present tumor was a conglomerate of multiple myxomatous nodules and its growing edge had a thick capsule, a feature never seen in aggressive angiomyxomas (6 ).
Microscopically, all the above-mentioned myxomatous tumors were composed of spindle-shaped, stellate and plump oval cells in a myxomatous stroma. However, these myxomatous tumors show different quantities and patterns of vessel elements (1 -6 ). Cutaneous mucinosis and cutaneous myxoid cysts contain clefts and mucin pools, but few vessels. In contrast, superficial angiomyxomas, both in the myxoid and collagen-fiber-rich areas, show a scattered distribution of small to medium sized thin-walled blood vessels, but large caliber vessels, seen in aggressive angiomyxomas, are absent. Moreover, a plexiform capillary pattern, detected in some malignant soft tissue tumors containing myxomatous lesions, such as low-grade fibromyxoid sarcoma (12 ,13 ), myxofibrosarcoma (14 ) and myxoid malignant fibrous histiocytoma, was not seen (15 ).
Table 1
Immunohistochemically, one report has described stromal cells in superficial angiomyxomas as lacking desmin, whereas desmin was positive in all of 22 aggressive angiomyxomas examined (6 ); another report that included two cases in men described that desmin was positive in the spindle cells of the myxoid stroma (5 ). However, in another study, desmin was negative in neoplastic stromal cells, not only in superficial but also in aggressive angiomyxomas (4 ). In other words, immunohistochemical studies are not so helpful for differential diagnosis of these myxomatous tumors.
Recently, the benign neoplastic disease entity angiomyofibroblastoma has been proposed for tumors arising in the subcutaneous tissue of the vulva, vagina and possibly the scrotum, in individuals ranging in age from 25 to 66 years (16 ,17 ). Although the tumor border macroscopically mimicks that of superficial angiomyxoma, angiomyofibroblastoma shows much higher neoplastic stromal cellularity than that of superficial angiomyxoma. Moreover, the neoplastic cells in angiomyofibroblastoma are positive for desmin (16 ).
In addition, Allen et al. proposed that the disease entity `superficial angiomyxomas' should include cutaneous focal mucinosis, trichodiscoma, fibrofolliculoma, perifollicular fibroma, trichofolliculoma and trichogenic adnexal tumor including trichogenic myxoma (1 ), although the significance of epithelial elements in the latter group of tumors has not been elucidated. However, we considered it better to exclude not only cutaneous focal mucinosis but also the additional tumors mentioned above from superficial angiomyxoma. Trichodiscoma, fibrofolliculoma and perifollicular fibroma are benign pilosebaceous mesenchymal neoplasms recapitulating the hair disk, fibrous sheath or papilla, and they are included within the disease entity `follicular fibroma' (18 ). Follicular fibromas contain mucin, but true myxoid cells are not present (18 ). There have been no reports of trichofolliculomas with true myxoid cells. We have found one case report of multiple trichogenic adnexal tumors including trichogenic myxomas composed of vascular myxoid connective tissue (19 ). However, all their stromal cells were not ordinary dermal fibroblasts, but originated from the fibrous sheath or mesenchymal papilla of hair follicles (19 ). For these reasons, we propose that the neoplasms mentioned above should not be considered forms of superficial angiomyxoma.
The authors are grateful to Ms. Eriko Miyazaki, Ms. Hisayo Yamasaki, Ms. Miko Mitani, Mr. Yoshihiro Hayashi and Mr. Tadatoshi Tokaji, First Department of Pathology, Kochi Medical School, and Ms. Naoyo Ohno and Ms. Yoshi Nabeshima, Chikamori Hospital, Kochi Prefecture, for their excellent technical assistance.
Antibody
Specificity
Source
1A4
Alpha-smooth muscle actin
DAKO Japan, Kyoto
DER-R-11
Desmin
Novocastra, Newcastle, United Kingdom
V9
Vimentin
DAKO Japan, Kyoto
HPCA-1
CD34
Nippon Beckton Dickinson, Tokyo
anti-S-100*
S-100 protein
DAKO Japan, Kyoto
References
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Copyright© Japanese Journal of Clinical Oncology, 1997.
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