- Email: [email protected]
Magnetic resonance imaging features of angiomyofibroblastoma-like tumor of the scrotum with pathologic correlates
Clinical Imaging 36 (2012) 632 – 635
Magnetic resonance imaging features of angiomyofibroblastoma-like tumor of the scrotum with pathologic correlates Mitsunari Maruyamaa , Takeshi Yoshizakoa,⁎, Hajime Kitagakia , Asuka Arakib , Mikio Igawac a Department of Radiology, Shimane University Faculty of Medicine, P.O. Box 00693-8501, 89-1 Enya Izumo, Japan Department of Organ Pathology, Shimane University Faculty of Medicine, P.O. Box 00693-8501, 89-1 Enya Izumo, Japan c Department of Urology, Shimane University Faculty of Medicine, P.O. Box 00693-8501, 89-1 Enya Izumo, Japan
b
Received 12 August 2011; received in revised form 2 September 2011; accepted 21 November 2011
Abstract Various tumors can occur in the scrotum. Among them, angiomyofibroblastoma-like tumors are very rare mesenchymal tumors. We report a case of an angiomyofibroblastoma-like tumor that arose in the right half of the scrotum in a 72-year-old man. It is difficult to separate angiomyofibroblastoma-like tumors from other malignant tumors invading the male genital tract on the basis of clinical characteristics and magnetic resonance imaging findings. © 2012 Elsevier Inc. All rights reserved. Keywords: Angiomyofibroblastoma-like tumor; Cellular angiofibroma; Scrotum; Magnetic resonance imaging
1. Introduction
2. Case report
Angiomyofibroblastoma is a rare tumor that arises in the genital tract, vulva, perineum, and pelvis in women, while angiomyofibroblastoma-like tumors are known to occur at sites such as the inguinal region, scrotum, and perineum in men. In 1997, Nucci et al. [1] first described angiomyofibroblastoma-like tumor as a cellular angiofibroma. In 1998, Laskin et al. [2] proposed the name of angiomyofibroblastoma-like tumor. Although it has been suggested that these tumors may arise from perivascular stem cells with a capacity for fatty and myofibroblastic differentiation, the histogenesis remains unknown. To our knowledge, there have been few reports on the magnetic resonance (MR) imaging features of this tumor. Here, we report a case of angiomyofibroblastoma-like tumor together with the MR imaging findings and a review of the literature.
A 72-year-old man presented with the chief complaint of a mass in the right half of the scrotum for 5 years that was slowly enlarging. He had a past history of stroke (15 years ago) and hypertension, for which he was receiving medical treatment. The patient had also suffered from hypertensive end-stage renal disease for 8 years and was receiving hemodialysis three times a week. On examination at the time of admission, a soft, mobile, nontender mass was palpable in the right scrotum that could not be differentiated from the testis. Tumor markers were all found to be normal, including alpha-fetoprotein, beta-human chorionic gonadotropin, and lactate dehydrogenase. The patient was referred for scrotal ultrasound imaging, which was performed with a grayscale unit and a 7–14-MHz linear array probe. Ultrasound demonstrated a poorly circumscribed, echogenic extratesticular mass (72×55×22 mm) in the right half of the scrotal sac (Fig. 1). No abnormalities of the bilateral testes were detected. These findings were inconclusive with regard to both intratesticular and extratesticular diseases, so MR imaging was suggested for further evaluation.
⁎ Corresponding author. Department of Radiology, Shimane University Faculty of Medicine, P.O. Box 00693-8501, 89-1 Enya Izumo, Japan. Tel.: +81 853 20 2289; fax: +81 853 20 2285. E-mail address: [email protected] (T. Yoshizako). 0899-7071/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2011.11.026
M. Maruyama et al. / Clinical Imaging 36 (2012) 632–635
633
Fig. 1. Scrotal ultrasound imaging is performed with a grayscale unit and a 7–14-MHz linear array probe. Ultrasound demonstrates a poorly circumscribed, echogenic extratesticular mass (72×55×22 mm) in the right half of the scrotal sac.
Fig. 2. (A) Axial T2-weighted (TR/TE, 5130/100) magnetic resonance (MR) image demonstrates a mass in the scrotal wall. The mass shows a heterogeneous intermediate to high signal intensity. (B) Axial T1-weighted (TR/TE, 500/9) MR image shows foci of high signal intensity that might represent fat (arrow). Otherwise, the signal intensity is similar to or lower than that of skeletal muscle. (C) Axial fat-suppressed T1-weighted (TR 550/TE 10) gadolinium-enhanced MR image demonstrates strong, but heterogeneous enhancement. (D) High b-value (b=1000 s/mm2) diffusion-weighted axial image (TR/TE/TI=4691/74/180; short TI recovery for fat suppression) does not show a marked increase of intensity throughout the lesion.
634
M. Maruyama et al. / Clinical Imaging 36 (2012) 632–635
Fig. 3. Photomicrograph reveals proliferation of spindle cells and numerous small- to medium-sized round vessels with a myxoid stroma containing collagen fibers (hematoxylin and eosin staining, ×100).
showed heterogeneous enhancement (Fig. 2C). Diffusionweighted images (DWI) did not reveal a marked increase of intensity throughout the lesion (Fig. 2D). A scrotal tumor was suspected, and biopsy revealed a pathological diagnosis of sarcoma. The patient was scheduled for scrotal exploration by the urologic surgeon, and right scrotum resection was undergone. It was found that the mass had no relation to the right testis. On histological examination, the tumor featured proliferation of spindle cells and numerous small- to medium-sized round vessels within a myxoid stroma containing collagen fibers (Fig. 3). There was little fatty tissue. On immunohistochemical staining, the spindle-shaped cells were positive for CD34, but were negative for desmin, smooth muscle actin, and S-100 protein. These findings were characteristic of angiomyofibroblastoma-like tumor.
3. Discussion Scrotal MR imaging was performed with a 1.5-T superconducting unit (GE, Milwaukee, WI, USA). The protocol involved acquisition of turbo spin-echo T2weighted (TR/TE, 5130/100) axial images and spin-echo T1-weighted (TR/TE, 500/9) axial images. Axial fatsuppressed spin-echo T1-weighted (TR/TE, 863/13) images were also acquired after intravenous administration of gadopentetate dimeglumine (0.1 μmol/kg). Moreover, high b-value (b=1000 s/mm 2) single-shot echo-planar diffusionweighted axial images (TR/TE/TI=4691/74/180; short TI recovery for fat suppression) were obtained. MR imaging demonstrated that the mass was located in the scrotal wall (Fig. 2A). T1-weighted images showed high signal intensity spot suggestive of foci resembling fat, while the intensity of the rest of the mass was similar to or lower than that of skeletal muscle (Fig. 2B). On T2-weighted images, the mass displayed a heterogeneous intermediate to high signal intensity (Fig. 2A). On enhanced MR images, the mass
Angiomyofibroblastoma has been described as a superficial tumor of the vulva that is distinct from the aggressive angiomyxoma reported by Fletcher et al. [3]. Angiomyofibroblastoma-like tumor was first described by Laskin et al. [2] in 1998 as a mesenchymal tumor of the male genital tract that resembles female angiomyofibroblastoma. Cellular angiofibroma was first described by Nucci et al. [1] in 1997 as a distinctive benign soft tissue tumor of the vulva that was distinguishable from angiomyofibroblastoma. Angiomyofibroblastoma-like tumor and cellular angiofibroma are considered to be similar entities, and Iwasa and Fletcher [4] have reported 51 cases of cellular angiofibroma occurring in both sexes, including angiomyofibroblastomalike tumors. Angiomyofibroblastoma-like tumor is a rare mesenchymal tumor. It usually occurs during the fifth to eighth decade of life and mainly involves the inguinoscrotal region.
Table 1 MR imaging characteristics of angiomyofibroblastoma-like tumor and the top differential diagnosis Disease
Location
Signal intensity on T2-weighted imaging
Signal intensity on T1-weighted imaging compared to muscle
Contrast enhancement
Others
Angiomyofibroblastomalike tumor Liposarcoma
Inguinoscrotal subcutaneous region Deep soft tissue
Slightly inhomogeneous high signal intensity High signal intensity
Similar to or lower signal intensity Low signal intensity
Intense enhancement
Contained foci fat A variety amount of fat
Spindle cell lipoma
Subcutaneous tissue
Isointense
Solitary fibrous tumor
A wide variety of soft tissue locations Perivascular growth
Similar to or greater than the signal intensity of fat Intermediate to high signal intensity Slightly inhomogeneous high signal intensity
Homogeneous or heterogeneous enhancement Intense enhancement
Low signal intensity to isointensity Similar to or lower signal intensity
Intense enhancement
–
Intense enhancement
High signal intensity
Isointense
Similar to angiomyofibroblastomalike tumor A whorled signal intensity pattern
Angiomyofibroblastoma
Aggressive angiomyxoma
Inguinal region of men, infiltrative growth pattern
Heterogeneous enhancement
–
M. Maruyama et al. / Clinical Imaging 36 (2012) 632–635
Clinically, the tumor is asymptomatic, well circumscribed, and grows slowly. It is typically composed of bland spindle cells arranged in short bundles or haphazardly, as well as collagen fibers and numerous small- to medium-sized vessels. Fat is present in 24–56% of these tumors and does not appear to be a prominent feature [2,4]. Immunohistochemically, the tumor cells are positive for CD34 in more than half of all reported cases and are occasionally positive for desmin, muscle-specific actin, smooth-muscle actin, estrogen receptor protein, and progesterone receptor protein, but are negative for S-100 protein [2,4]. The present case had a history, examination findings, and pathology findings consistent with previous reports [2,4]. A few reports [5,6] have suggested that angiomyofibroblastoma-like tumor is mainly hyperintense on T2-weighted MR images, with slightly inhomogeneous intensity depending on the content of spindle cells, collagenous stroma, myxoid matrix, and fatty tissue. T1-weighted images may show foci of high signal intensity that indicate fat [5]. Angiomyofibroblastoma-like tumor may also display intense enhancement owing to its rich vascularity. The imaging findings of our patient were in agreement with these previous reports. We also obtained high b-value diffusion-weighted images in the present patient. A low signal intensity on high b-value diffusion-weighted images may suggest that a lesion is of low grade, as has been shown in other tumors [7]. And the scrotum exists adjacent to the air. The quality of DWI might be limited in the scrotal region due to susceptibility effect. However, it can be difficult to distinguish other lipomatous, fibromyxoid, or angiomyxoid tumors from angiomyofibroblastoma-like tumor on the basis of imaging findings [5,6], so tissue sampling and surgical resection of the lesion may be necessary [6]. Table 1 shows the MR imaging characteristics of this tumor and the top differential diagnosis. Angiomyofibroblastoma contains spindle cells or epithelioid cells within an edematous loose collagen stroma and also features prominent thin-walled vessels. The tumor cells exhibit a tendency for perivascular growth. On immunohistochemical examination, desmin is detected in most reported cases [1,8]. The imaging findings of angiomyofibroblastoma have rarely been reported. It exhibits a high signal intensity on T2-weighted MR images but may appear slightly inhomogeneous because of variations in the content of tumor cells, collagenous stroma, and adipose tissue [9]. These radiological and pathological features are similar to those of angiomyofibroblastoma-like tumor [5]. Because the imaging features of both angiomyofibroblastoma and angiomyofibroblastoma-like tumor are nonspecific [5,9], it may be difficult to distinguish these lesions from other soft tissue tumors [5,6].
635
Aggressive angiomyxomas resemble angiomyofibroblastomas and angiomyofibroblastoma-like tumors in many ways, except for an infiltrative growth pattern, lower cellularity in a myxoid stroma, and less conspicuous vascularity. Aggressive angiomyxoma displays a high signal intensity on T2-weighted MR images, heterogeneous contrast enhancement, and a whorled signal intensity pattern that is related to the myxoid matrix with a characteristic internal swirl. MR imaging can also demonstrate the growth pattern of these tumors, such as translevator extension and expansion around the pelvic organs [10]. Despite the reported features that suggest it may be possible to distinguish different tumors by MR imaging, it is actually difficult to confidently predict the nature and precise etiology of these neoplasms based on imaging alone. Additional imaging modalities would not have been likely to add any more useful information, so tissue sampling and surgical removal of the lesion are probably necessary. In the present patient, MR imaging findings and histological features were correlated, as confirmed after tumor resection. References [1] Nucci MR, Granter SR, Fletcher CDM. Cellular angiofibroma: a benign neoplasm distinct from angiomyofibroblastoma and spindle cell lipoma. Am J Surg Pathol 1997;21:636–44. [2] Laskin WB, Fetsch JF, Mostofi FK. Angiomyofibroblastoma-like tumor of the male genital tract: analysis of 11 cases with comparison to female angiomyofibroblastoma and spindle cell lipoma. Am J Surg Pathol 1998;22:6–16. [3] Fletcher CDM, Tsang WYW, Fisher C, Lee KC, Chan JKC. Angiomyofibroblastoma of the vulva. A benign neoplasm distinct from aggressive angiomyxoma. Am J Surg Pathol 1992;16:373–82. [4] Iwasa Y, Fletcher CDM. Cellular angiofibroma: clinicopathologic and immunohistochemical analysis of 51 cases. Am J Surg Pathol 2004;28: 1426–35. [5] Miyajima K, Hasegawa S, Oda Y, Toyoshima S, Tsuneyoshi M, Motooka M, et al. Angiomyofibroblastoma-like tumor (cellular angiofibroma) in the male inguinal region. Radiat Med 2007;25: 173–7. [6] Koo PJ, Goykhman I, Lembert L, Nunes LW. MRI features of cellular angiomyofibroma with pathologic correlation. J Magn Reson Imaging 2009;29:1195–8. [7] Tamai K, Koyama T, Saga T, Morisawa N, Fujimoto K, Mikami Y, et al. The utility of diffusion-weighted MR imaging for differentiating uterine sarcomas from benign leiomyomas. Eur Radiol 2008;18: 723–30. [8] Laskin WB, Fetsch JF, Tavassoli FA. Angiomyofibroblastoma of the female genital tract: analysis of 17 cases including a lipomatous variant. Hum Pathol 1997;28:1046–55. [9] Geng J, Hu S, Wang F. Large paravaginal angiomyofibroblastoma: magnetic resonance imaging findings. Jpn J Radiol 2011;29:152–5. [10] Sinha R, Verma R. Case 106: aggressive angiomyxoma. Radiology 2007;242:625–7.
Magnetic resonance imaging features of angiomyofibroblastoma-like tumor of the scrotum with pathologic correlates Mitsunari Maruyamaa , Takeshi Yoshizakoa,⁎, Hajime Kitagakia , Asuka Arakib , Mikio Igawac a Department of Radiology, Shimane University Faculty of Medicine, P.O. Box 00693-8501, 89-1 Enya Izumo, Japan Department of Organ Pathology, Shimane University Faculty of Medicine, P.O. Box 00693-8501, 89-1 Enya Izumo, Japan c Department of Urology, Shimane University Faculty of Medicine, P.O. Box 00693-8501, 89-1 Enya Izumo, Japan
b
Received 12 August 2011; received in revised form 2 September 2011; accepted 21 November 2011
Abstract Various tumors can occur in the scrotum. Among them, angiomyofibroblastoma-like tumors are very rare mesenchymal tumors. We report a case of an angiomyofibroblastoma-like tumor that arose in the right half of the scrotum in a 72-year-old man. It is difficult to separate angiomyofibroblastoma-like tumors from other malignant tumors invading the male genital tract on the basis of clinical characteristics and magnetic resonance imaging findings. © 2012 Elsevier Inc. All rights reserved. Keywords: Angiomyofibroblastoma-like tumor; Cellular angiofibroma; Scrotum; Magnetic resonance imaging
1. Introduction
2. Case report
Angiomyofibroblastoma is a rare tumor that arises in the genital tract, vulva, perineum, and pelvis in women, while angiomyofibroblastoma-like tumors are known to occur at sites such as the inguinal region, scrotum, and perineum in men. In 1997, Nucci et al. [1] first described angiomyofibroblastoma-like tumor as a cellular angiofibroma. In 1998, Laskin et al. [2] proposed the name of angiomyofibroblastoma-like tumor. Although it has been suggested that these tumors may arise from perivascular stem cells with a capacity for fatty and myofibroblastic differentiation, the histogenesis remains unknown. To our knowledge, there have been few reports on the magnetic resonance (MR) imaging features of this tumor. Here, we report a case of angiomyofibroblastoma-like tumor together with the MR imaging findings and a review of the literature.
A 72-year-old man presented with the chief complaint of a mass in the right half of the scrotum for 5 years that was slowly enlarging. He had a past history of stroke (15 years ago) and hypertension, for which he was receiving medical treatment. The patient had also suffered from hypertensive end-stage renal disease for 8 years and was receiving hemodialysis three times a week. On examination at the time of admission, a soft, mobile, nontender mass was palpable in the right scrotum that could not be differentiated from the testis. Tumor markers were all found to be normal, including alpha-fetoprotein, beta-human chorionic gonadotropin, and lactate dehydrogenase. The patient was referred for scrotal ultrasound imaging, which was performed with a grayscale unit and a 7–14-MHz linear array probe. Ultrasound demonstrated a poorly circumscribed, echogenic extratesticular mass (72×55×22 mm) in the right half of the scrotal sac (Fig. 1). No abnormalities of the bilateral testes were detected. These findings were inconclusive with regard to both intratesticular and extratesticular diseases, so MR imaging was suggested for further evaluation.
⁎ Corresponding author. Department of Radiology, Shimane University Faculty of Medicine, P.O. Box 00693-8501, 89-1 Enya Izumo, Japan. Tel.: +81 853 20 2289; fax: +81 853 20 2285. E-mail address: [email protected] (T. Yoshizako). 0899-7071/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.clinimag.2011.11.026
M. Maruyama et al. / Clinical Imaging 36 (2012) 632–635
633
Fig. 1. Scrotal ultrasound imaging is performed with a grayscale unit and a 7–14-MHz linear array probe. Ultrasound demonstrates a poorly circumscribed, echogenic extratesticular mass (72×55×22 mm) in the right half of the scrotal sac.
Fig. 2. (A) Axial T2-weighted (TR/TE, 5130/100) magnetic resonance (MR) image demonstrates a mass in the scrotal wall. The mass shows a heterogeneous intermediate to high signal intensity. (B) Axial T1-weighted (TR/TE, 500/9) MR image shows foci of high signal intensity that might represent fat (arrow). Otherwise, the signal intensity is similar to or lower than that of skeletal muscle. (C) Axial fat-suppressed T1-weighted (TR 550/TE 10) gadolinium-enhanced MR image demonstrates strong, but heterogeneous enhancement. (D) High b-value (b=1000 s/mm2) diffusion-weighted axial image (TR/TE/TI=4691/74/180; short TI recovery for fat suppression) does not show a marked increase of intensity throughout the lesion.
634
M. Maruyama et al. / Clinical Imaging 36 (2012) 632–635
Fig. 3. Photomicrograph reveals proliferation of spindle cells and numerous small- to medium-sized round vessels with a myxoid stroma containing collagen fibers (hematoxylin and eosin staining, ×100).
showed heterogeneous enhancement (Fig. 2C). Diffusionweighted images (DWI) did not reveal a marked increase of intensity throughout the lesion (Fig. 2D). A scrotal tumor was suspected, and biopsy revealed a pathological diagnosis of sarcoma. The patient was scheduled for scrotal exploration by the urologic surgeon, and right scrotum resection was undergone. It was found that the mass had no relation to the right testis. On histological examination, the tumor featured proliferation of spindle cells and numerous small- to medium-sized round vessels within a myxoid stroma containing collagen fibers (Fig. 3). There was little fatty tissue. On immunohistochemical staining, the spindle-shaped cells were positive for CD34, but were negative for desmin, smooth muscle actin, and S-100 protein. These findings were characteristic of angiomyofibroblastoma-like tumor.
3. Discussion Scrotal MR imaging was performed with a 1.5-T superconducting unit (GE, Milwaukee, WI, USA). The protocol involved acquisition of turbo spin-echo T2weighted (TR/TE, 5130/100) axial images and spin-echo T1-weighted (TR/TE, 500/9) axial images. Axial fatsuppressed spin-echo T1-weighted (TR/TE, 863/13) images were also acquired after intravenous administration of gadopentetate dimeglumine (0.1 μmol/kg). Moreover, high b-value (b=1000 s/mm 2) single-shot echo-planar diffusionweighted axial images (TR/TE/TI=4691/74/180; short TI recovery for fat suppression) were obtained. MR imaging demonstrated that the mass was located in the scrotal wall (Fig. 2A). T1-weighted images showed high signal intensity spot suggestive of foci resembling fat, while the intensity of the rest of the mass was similar to or lower than that of skeletal muscle (Fig. 2B). On T2-weighted images, the mass displayed a heterogeneous intermediate to high signal intensity (Fig. 2A). On enhanced MR images, the mass
Angiomyofibroblastoma has been described as a superficial tumor of the vulva that is distinct from the aggressive angiomyxoma reported by Fletcher et al. [3]. Angiomyofibroblastoma-like tumor was first described by Laskin et al. [2] in 1998 as a mesenchymal tumor of the male genital tract that resembles female angiomyofibroblastoma. Cellular angiofibroma was first described by Nucci et al. [1] in 1997 as a distinctive benign soft tissue tumor of the vulva that was distinguishable from angiomyofibroblastoma. Angiomyofibroblastoma-like tumor and cellular angiofibroma are considered to be similar entities, and Iwasa and Fletcher [4] have reported 51 cases of cellular angiofibroma occurring in both sexes, including angiomyofibroblastomalike tumors. Angiomyofibroblastoma-like tumor is a rare mesenchymal tumor. It usually occurs during the fifth to eighth decade of life and mainly involves the inguinoscrotal region.
Table 1 MR imaging characteristics of angiomyofibroblastoma-like tumor and the top differential diagnosis Disease
Location
Signal intensity on T2-weighted imaging
Signal intensity on T1-weighted imaging compared to muscle
Contrast enhancement
Others
Angiomyofibroblastomalike tumor Liposarcoma
Inguinoscrotal subcutaneous region Deep soft tissue
Slightly inhomogeneous high signal intensity High signal intensity
Similar to or lower signal intensity Low signal intensity
Intense enhancement
Contained foci fat A variety amount of fat
Spindle cell lipoma
Subcutaneous tissue
Isointense
Solitary fibrous tumor
A wide variety of soft tissue locations Perivascular growth
Similar to or greater than the signal intensity of fat Intermediate to high signal intensity Slightly inhomogeneous high signal intensity
Homogeneous or heterogeneous enhancement Intense enhancement
Low signal intensity to isointensity Similar to or lower signal intensity
Intense enhancement
–
Intense enhancement
High signal intensity
Isointense
Similar to angiomyofibroblastomalike tumor A whorled signal intensity pattern
Angiomyofibroblastoma
Aggressive angiomyxoma
Inguinal region of men, infiltrative growth pattern
Heterogeneous enhancement
–
M. Maruyama et al. / Clinical Imaging 36 (2012) 632–635
Clinically, the tumor is asymptomatic, well circumscribed, and grows slowly. It is typically composed of bland spindle cells arranged in short bundles or haphazardly, as well as collagen fibers and numerous small- to medium-sized vessels. Fat is present in 24–56% of these tumors and does not appear to be a prominent feature [2,4]. Immunohistochemically, the tumor cells are positive for CD34 in more than half of all reported cases and are occasionally positive for desmin, muscle-specific actin, smooth-muscle actin, estrogen receptor protein, and progesterone receptor protein, but are negative for S-100 protein [2,4]. The present case had a history, examination findings, and pathology findings consistent with previous reports [2,4]. A few reports [5,6] have suggested that angiomyofibroblastoma-like tumor is mainly hyperintense on T2-weighted MR images, with slightly inhomogeneous intensity depending on the content of spindle cells, collagenous stroma, myxoid matrix, and fatty tissue. T1-weighted images may show foci of high signal intensity that indicate fat [5]. Angiomyofibroblastoma-like tumor may also display intense enhancement owing to its rich vascularity. The imaging findings of our patient were in agreement with these previous reports. We also obtained high b-value diffusion-weighted images in the present patient. A low signal intensity on high b-value diffusion-weighted images may suggest that a lesion is of low grade, as has been shown in other tumors [7]. And the scrotum exists adjacent to the air. The quality of DWI might be limited in the scrotal region due to susceptibility effect. However, it can be difficult to distinguish other lipomatous, fibromyxoid, or angiomyxoid tumors from angiomyofibroblastoma-like tumor on the basis of imaging findings [5,6], so tissue sampling and surgical resection of the lesion may be necessary [6]. Table 1 shows the MR imaging characteristics of this tumor and the top differential diagnosis. Angiomyofibroblastoma contains spindle cells or epithelioid cells within an edematous loose collagen stroma and also features prominent thin-walled vessels. The tumor cells exhibit a tendency for perivascular growth. On immunohistochemical examination, desmin is detected in most reported cases [1,8]. The imaging findings of angiomyofibroblastoma have rarely been reported. It exhibits a high signal intensity on T2-weighted MR images but may appear slightly inhomogeneous because of variations in the content of tumor cells, collagenous stroma, and adipose tissue [9]. These radiological and pathological features are similar to those of angiomyofibroblastoma-like tumor [5]. Because the imaging features of both angiomyofibroblastoma and angiomyofibroblastoma-like tumor are nonspecific [5,9], it may be difficult to distinguish these lesions from other soft tissue tumors [5,6].
635
Aggressive angiomyxomas resemble angiomyofibroblastomas and angiomyofibroblastoma-like tumors in many ways, except for an infiltrative growth pattern, lower cellularity in a myxoid stroma, and less conspicuous vascularity. Aggressive angiomyxoma displays a high signal intensity on T2-weighted MR images, heterogeneous contrast enhancement, and a whorled signal intensity pattern that is related to the myxoid matrix with a characteristic internal swirl. MR imaging can also demonstrate the growth pattern of these tumors, such as translevator extension and expansion around the pelvic organs [10]. Despite the reported features that suggest it may be possible to distinguish different tumors by MR imaging, it is actually difficult to confidently predict the nature and precise etiology of these neoplasms based on imaging alone. Additional imaging modalities would not have been likely to add any more useful information, so tissue sampling and surgical removal of the lesion are probably necessary. In the present patient, MR imaging findings and histological features were correlated, as confirmed after tumor resection. References [1] Nucci MR, Granter SR, Fletcher CDM. Cellular angiofibroma: a benign neoplasm distinct from angiomyofibroblastoma and spindle cell lipoma. Am J Surg Pathol 1997;21:636–44. [2] Laskin WB, Fetsch JF, Mostofi FK. Angiomyofibroblastoma-like tumor of the male genital tract: analysis of 11 cases with comparison to female angiomyofibroblastoma and spindle cell lipoma. Am J Surg Pathol 1998;22:6–16. [3] Fletcher CDM, Tsang WYW, Fisher C, Lee KC, Chan JKC. Angiomyofibroblastoma of the vulva. A benign neoplasm distinct from aggressive angiomyxoma. Am J Surg Pathol 1992;16:373–82. [4] Iwasa Y, Fletcher CDM. Cellular angiofibroma: clinicopathologic and immunohistochemical analysis of 51 cases. Am J Surg Pathol 2004;28: 1426–35. [5] Miyajima K, Hasegawa S, Oda Y, Toyoshima S, Tsuneyoshi M, Motooka M, et al. Angiomyofibroblastoma-like tumor (cellular angiofibroma) in the male inguinal region. Radiat Med 2007;25: 173–7. [6] Koo PJ, Goykhman I, Lembert L, Nunes LW. MRI features of cellular angiomyofibroma with pathologic correlation. J Magn Reson Imaging 2009;29:1195–8. [7] Tamai K, Koyama T, Saga T, Morisawa N, Fujimoto K, Mikami Y, et al. The utility of diffusion-weighted MR imaging for differentiating uterine sarcomas from benign leiomyomas. Eur Radiol 2008;18: 723–30. [8] Laskin WB, Fetsch JF, Tavassoli FA. Angiomyofibroblastoma of the female genital tract: analysis of 17 cases including a lipomatous variant. Hum Pathol 1997;28:1046–55. [9] Geng J, Hu S, Wang F. Large paravaginal angiomyofibroblastoma: magnetic resonance imaging findings. Jpn J Radiol 2011;29:152–5. [10] Sinha R, Verma R. Case 106: aggressive angiomyxoma. Radiology 2007;242:625–7.