DOI: 10.1148/radiol.2422040656
(Radiology 2007;242:625-627.)
© RSNA, 2007
Case 106: Aggressive Angiomyxoma1
Rakesh Sinha, MD, FRCR and
Ratan Verma, MRCP, FRCR
1 From the Department of Radiology, Glenfield Hospital, Groby Rd, Leicester LE3 9QP, England. Received April 9, 2004; revision requested June 18; revision received June 25; accepted July 27; final version accepted August 3.
Correspondence: Address correspondence to R.S. (e-mail: rakesh{at}rsinha.freeserve.co.uk)
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HISTORY
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A 46-year-old woman presented with perineal discomfort, dyspareunia, and a slowly growing mass in the perineal region. The signs and symptoms had been present for the past 6 months and had initially begun with intermittent swelling in the perineum. The patient's medical history included total abdominal hysterectomy for fibroids. The ovaries were preserved.
At examination, swelling overlying the left ischial tuberosity was visible. A vaginal examination revealed a posterior mass in the left labia majorum. The mass felt cystic at palpation. Magnetic resonance (MR) imaging of the pelvis was performed.
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IMAGING FINDINGS
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MR imaging revealed a well-defined 3 x 3-cm mass arising from the posterior portion of the left labia that was isointense to muscle on T1-weighted images (Fig 1). High signal intensity was present within the mass on T2-weighted and fat-suppressed images (Figs 2, 3), with avid enhancement after administration of gadobenate dimeglumine (Multihance; Bracco, Bucks, England) (Fig 4). The mass also demonstrated a whorled pattern of signal intensity, particularly on the T2-weighted and contrast material–enhanced images. The lesion appeared to be displacing rather than infiltrating the adjacent soft tissue.
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Figure 1: Transverse T1-weighted spin-echo (repetition time msec/echo time msec, 115/14) MR image of the perineal region shows an isointense mass (arrow) arising from the labia. The mass is displacing rather than infiltrating the adjacent fat planes.
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Figure 4: Transverse fat-suppressed T1-weighted spin-echo (115/4) contrast-enhanced MR image of the perineum shows the whorled signal intensity pattern and enhancement of the lesion (arrow).
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DISCUSSION
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The mass was surgically excised and was shown to be an aggressive angiomyxoma at histologic analysis. Aggressive angiomyxomas occur (a) almost exclusively in the genital and perineal area of female patients and (b) most commonly in the 3rd–5th decades of life (1). Rare cases of aggressive angiomyxomas in male patients have also been reported. Most tumors are large (usually larger than 10 cm) and grow slowly. Signs and symptoms at presentation may include discomfort from the mass, a visible mass, or pressure effects on adjacent pelvic organs.
At pathologic analysis, aggressive angiomyxomas are poorly circumscribed lesions composed of stellate and spindle-shaped cells distributed in a myxoid matrix. The lesions have an abundant supply of vessels that are often thickened or hyalinized.
The MR features of perineal aggressive angiomyxomas have been described previously and consist of isointense or low-signal-intensity findings on T1-weighted images and high-signal-intensity findings on T2-weighted images (2,3). The high signal intensity seen on T2-weighted images reflects the high myxomatous content of these tumors (4). A whorled pattern of signal intensity on T2-weighted images has been reported as a typical feature of aggressive angiomyxomas (5,6). These tumors also show contrast enhancement that reflects their inherent vascularity. On MR images, these tumors typically do not show an infiltrative pattern and tend to displace and grow around adjacent structures. The images obtained in our patient showed these features. Whorled signal intensity was well demonstrated on the fat-suppressed T2-weighted and postcontrast T1-weighted images.
The possible differential diagnosis of Bartholin cyst was ruled out, as these cysts do not typically show strong enhancement after contrast agent administration and they do not have a typical whorled pattern of signal intensity on MR images (7). An infected Bartholin or pilonidal cyst may show complex signal intensity and contrast enhancement on postcontrast MR images (7,8). However, in such cases there is usually peripheral enhancement of the wall of the cyst with a necrotic nonenhancing center. Furthermore, in patients with a pilonidal cyst, there may be clinical and imaging findings of an associated pilonidal sinus.
Other differential diagnoses to consider include lipomas, vaginal myomas, endometriomas, and other malignant tumors. Unlike the findings in this patient, myomas tend to have low signal intensity on T2-weighted images with uniform enhancement; this is generally considered a pathognomic finding (9). Lipomas would be expected to show signal intensity dropout on fat-suppressed images. Endometriomas have a characteristic appearance on MR images. They show high signal intensity on T1-weighted images because of contained methemoglobin, blood products, or concentrated proteins (10). An important imaging characteristic of endometriomas is shading (loss of signal intensity within the lesion) on T2-weighted images. Shading is due to the chronic nature of these lesions, with cyclical depositions of blood products and proteins that shorten the T2 relaxation time (10).
Malignant tumors—such as melanomas, rhabdomyosarcomas, and squamous cell carcinomas—can also occur in the perineal region. Melanomas may show high signal intensity on T1-weighted images because of internal hemorrhage or melanin content (11). Rhabdomyosarcomas usually occur in younger patients, and squamous cell carcinomas tend to have an infiltrative appearance with invasion into deeper parametrial structures (12,13). None of these tumors would be expected to demonstrate whorled T2-weighted high signal intensity, as was reported in this patient.
The treatment for aggressive angiomyxoma is wide local excision. Incomplete excision leads to local recurrence in up to 30% of cases. To our knowledge, there have been no reported cases of distant metastases from aggressive angiomyxomas.
In summary, aggressive angiomyxomas have a characteristic MR imaging appearance. Typically, an aggressive angiomyxoma will appear in a woman as a perineal mass with high signal intensity on T2-weighted MR images, heterogeneous contrast enhancement, and a whorled pattern of signal intensity. Furthermore, MR imaging can also demonstrate unusual growth patterns of these tumors, such as translevator extension and growth around pelvic organs. MR imaging also allows physicians to plan the best surgical route, such as a perineal or an abdominopelvic approach, for excision of these tumors (5).
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FOOTNOTES
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| Part one of this case appeared 4 months previously and may contain larger images.
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References
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- Davani M, Chablani VN, Saba PR. Aggressive angiomyxoma of pelvic soft tissues: MR imaging appearance. AJR Am J Roentgenol 1998;170:1113–1114.[Medline]
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- Siegelman ES, Outwater EK. Tissue characterization in the female pelvis by means of MR imaging. Radiology 1999;212:5–18.[Abstract/Free Full Text]
- Jeyadevan NN, Sohaib SA, Thomas JM, Jeyarajah A, Shepherd JH, Fischer C. Imaging features of aggressive angiomyxoma. Clin Radiol 2003;58:157–162.[CrossRef][Medline]
- Chien AJ, Freeby JA, Win TT, Gadwood KA. Aggressive angiomyxoma of the female pelvis: sonographic, CT and MR findings. AJR Am J Roentgenol 1998;171:530–531.[Free Full Text]
- Hahn WY, Israel GM, Lee VS. MRI of female urethral and periurethral disorders. AJR Am J Roentgenol 2004;182:677–682.[Free Full Text]
- Taylor SA, Halligan S, Bartram CI. Pilonidal sinus disease: MR imaging distinction from fistula in ano. Radiology 2003;226:662–667.[Abstract/Free Full Text]
- Murase E, Siegelman ES, Outwater EK, Perez-Jaffe LA, Tureck RW. Uterine leiomyomas: histopathologic features, MR imaging findings, differential diagnosis, and treatment. RadioGraphics 1999;19:1179–1197.[Abstract/Free Full Text]
- Woodward PJ, Sohaey R, Mezzetti TP Jr. Endometriosis: radiologic-pathologic correlation. RadioGraphics 2001;21:193–216.[Abstract/Free Full Text]
- Moon WK, Kim SH, Han MC. MR findings of malignant melanoma of the vagina. Clin Radiol 1993;48:326–328.[CrossRef][Medline]
- McCarville MB, Spunt SL, Pappo AS. Rhabdomyosarcoma in pediatric patients: the good, the bad, and the unusual. AJR Am J Roentgenol 2001;176:1563–1569.[Free Full Text]
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Congratulations to the 34 individuals and two resident groups that submitted the most likely diagnosis (aggressive angiomyxoma) for Diagnosis Please, Case 106. The names and locations of the individuals and resident groups, as submitted, are as follows:
Individual responses
- Eric Leigh Bressler, MD, Minnetonka, Minn
- Natesan Chidambaranathan, MD, Chennai, India
- Annapurneswara Rao Chimpiri, MD, Edmond, Okla
- Yves-Sebastien Cordoliani, MD, Chatenay Malabry, France
- Akira Fujikawa, MD, Setagaya, Tokyo, Japan
- Mark Gilbert Goldshein, MD, Andover, Mass
- Francisco Jose Gonzalez, MD, Santander, Spain
- Pramod Kumar Gupta, MD, Plano, Tex
- Soichiro Hase, Niihama, Japan
- Yuusuke Hirokawa, MD, Kyoto City, Japan
- Alberto Carlucci Iaia, MD, Wilmington, Del
- Sawako Kitahara, Otsu, Japan
- Mario A. Laguna, MD, Milwaukee, Wis
- Naganathan B. S. Mani, MD, Nassau, Bahamas
- Nikolaos Michailidis, MD, Thessaloniki, Greece
- Manabu Minami, MD, Tsukuba, Ibaraki, Japan
- Sankar R. Mondal, MD, Nassau, Bahamas
- Thomas Moser, MD, Strasbourg, France
- Mizuki Nishino, MD, Boston, Mass
- Hiroshi Nobusawa, MD, PhD, Ota, Tokyo, Japan
- Patrick Augustine O'Keeffe, MBBCh, Brookline, Mass
- Laura Oleaga, MD, Bilbao, Spain
- Carlos Ovejero Vela, MD, Barcelona, Spain
- Joseph Raymond Perno, MD, PhD, Hamilton, NJ
- Enrique Remartinez Escobar, MD, Melilla, Spain
- Tsutomu Sakamoto, MD, Tokyo, Japan
- Taro Shimono, MD, Sakai, Osaka, Japan
- Eliko Tanaka, MD, Yokohama, Kanagawa, Japan
- Eugene Tong, MD, Austin, Tex
- Özgür Tosun, Ankara, Turkey
- Eleni Vafeiadou, Thessaloniki, Greece
- Ricardo Luis Videla, Córdoba, Argentina
- Dengbin Wang, Shanghai, China
- Joe Yut, Olathe, Kan
Resident group responses
- University of Pennsylvania Radiology Residents, Philadelphia, Pa
- Virginia Commonwealth University Radiology Residents, Richmond, Va
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HISTORY
IMAGING FINDINGS
