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Imaging characteristics of calcified leiomyoma of deep soft tissue
J Orthop Sci (2007) 12:601–605 DOI 10.1007/s00776-007-1167-5
Case report Imaging characteristics of calcified leiomyoma of deep soft tissue YUJI MIKI1, SATOSHI ABE1, TORU TOKIZAKI1, ARIMI HARASAWA2, TETSUO IMAMURA3, and TAKASHI MATSUSHITA1 1 2 3
Department of Orthopaedic Surgery, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan Department of Surgical Pathology, Teikyo University School of Medicine, Tokyo, Japan
Introduction Leiomyoma of the deep soft tissue in the extremities is rare. Only 21 cases have been reported in the literature.1–14 Most of those had developed calcifications, which made the differential diagnosis difficult on imaging. Magnetic resonance imaging (MRI) findings of leiomyoma in the extremities have not been sufficiently documented in conjunction with the differential diagnosis. The purpose of this study was to document the correlation of MRI and histopathological findings of leiomyoma of deep soft tissue in the extremities and to discuss the possibility of reaching an exact imaging diagnosis.
Case report A 14-year-old girl was referred to our hospital for evaluation of a right great toe mass with continuous pain. The mass had been present for approximately 3 years and gradually grew larger. Physical examination revealed an approximately 3-cm, hard, tender mass at the base of the right great toe with an engorged superficial vein. There was no history of trauma, fever, or local heat. Routine laboratory studies were within normal limits. Plain radiographies showed multiple small, patchy calcifications within the tumor mass at the plantar aspect of the first proximal phalanx (Fig. 1). The tumor mass was well circumscribed and essentially isointense to neighboring muscles on T1-weighted MR images. On T2-weighted images, the signal intensity of the tumor was decreased, with isointensity to slightly hyperintensity. Spotty and punctuate signal void lesions were found within the tumor on both T1- and T2-weighted images
Offprint requests to: Y. Miki Received: April 3, 2007 / Accepted: June 28, 2007
(Fig. 2A,B). On Gd-DTPA-enhanced T1-weighted images, the tumor mass was enhanced homogeneously except for spotty low signal areas of calcification (Fig. 2C). The tumor showed marked contrast enhancement during the early phase. Dynamic Gd-enhanced MR study yielded time–intensity curves reflecting rates of gadolinium enhancement ranging from 394% to 546%/ min. A rapidly ascending slope was depicted on the time–intensity curve, which represented rich tumor vessels (Fig. 3). Our clinical diagnosis was benign well-marginated calcified soft tissue tumors including leiomyoma of deep soft tissue, calcifying neurilemoma, myositis ossificans, tumoral calcinosis, extraskeletal chondroma, and ossifying fibromyxoid tumor. The differential diagnoses also included synovial sarcoma, extraskeletal osteosarcoma, and extraskeletal mesenchymal chondrosarcoma. We choose careful excisional biopsy to avoid extensive contamination by incisional or needle biopsy because the tumor mass was small and close to the skin and digital nerves and vessels. Gross findings The tumor was attached to the flexor tendon of the great toe, but there was no adhesion to the skin. It was excised as an en bloc mass with related skin. The tumor was encapsulated, and its mass measured 28 × 25 × 30 mm. On opening the capsule, the tumor surface was grayish-white, and it was nodule-conglomerated with calcified nodules. Microscopic findings Histology of the surgical specimen showed fascicular multiplication of spindle cells with oval nuclei and prominent fascicles suggesting smooth muscle fibers. Foci of the calcification were prominent in the areas of degenerative changes, and hyalinization and a lobular
602
Y. Miki et al.: Leiomyoma of deep soft tissue
Ultrastructural findings The tumor cells were spindle-shaped with spindle- and rather amorphous-shaped nuclei and were surrounded by extracellular matrix consisted of abundant collagen fibers. The cytoplasm contained dense microfilaments, moderate amounts of rough endoplasmic reticulum, small vesicles, mitochondria, and glycogen particles. Dense bodies were frequently observed on microfilaments. Focal pinocytic vesicles and attachment plaques were present underneath the cell membrane. Basal laminae were seen along the cell membrane. These microscopic findings were compatible with leiomyoma (Fig. 6). The tumor was diagnosed as a benign leiomyoma of deep soft tissue. The patient made an uneventful postoperative recovery and was without recurrence 42 months after the surgery. The patient and her family were informed that the data from the case would be submitted for publication and gave their consent.
Discussion
Fig. 1. Radiograph showing multiple small calcifications in the tumor mass
fibrous septum was also observed. The mitotic rate was less than 3 mitotic figures per 50 high-power fields (HPF) without any cellular atypism (Fig. 4). Any correlation between MRI and histopathological findings was studied. Foci of rather decreased signal intensity on T2weighted images were compatible with the areas of degenerative pathological changes of hyalinization, fibrosis, necrosis, and calcification in the tumor. The tumor showed decreased signal intensity with iso- to slightly hyperintensity on T2-weighted images with prominent enhancement following contrast administration in the nonmineralized area of the lesion with moderate cellularity and hypervascularity. Immunohistochemical findings Vimentin (Dako, Glostrup, Denmark), SMA (Dako), and desmin (Dako) was found the cytoplasm of the spindle tumor cells. Immunoreactivity of CD-34 (Dako) was negative for tumor cells, but prominent vascularity was identified (Fig. 5A,B).
We compared histological and imaging findings. The tumor mass included multiple small calcifications in the soft tissue mass on plain radiography and spotty and punctuate signal void lesions on MRI. These lesions represented prominent foci of stromal dystrophic calcification on histological examination. The MR findings revealed the tumor mass to be essentially isointense to muscle on T1-weighted images and to have decreased signal intensity with iso- to relatively high intensity on T2-weighted images. The tumor showed prominent enhancement following contrast administration in the nonmineralized area with moderate cellularity and hypervascularity. Dynamic MR study depicted a rapidly ascending slope followed by a gradually descending slope. This type of time–intensity curve correlated with vascular and cellular lesions on histological examination.15 These imaging findings represented histological features of cellular areas with hypervascularity and coexisting regressive changes. In a comparison between malignant and benign soft tissue tumors that were operated on and had a dynamic MR imaging study, both enhancement during the early and late phases were higher in malignant tumors. However, some benign tumors, such as hemangioma, myositis ossificans, and aggressive fibromatosis, may show high contrast enhancement.16 The distinctive enhanced MR imaging characteristics in a synovial sarcoma revealed an early start of enhancement, peripheral tumoral enhancement, and rapid initial enhancement followed by a plateau or washout phase.17 Dynamic MR findings were valuable
Y. Miki et al.: Leiomyoma of deep soft tissue
603
B
A
Fig. 2. A T1-weighted (TR 600 ms, TE 9.7 ms) image. The tumor mass is isointense to the muscle with spotty signal voids. B T2-weighted (TR 3000 ms, TE 86.5 ms) image. The signal intensity of the tumor showed decreased signal intensity with iso- to relatively high intensity. C Gadoliniumdiethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced T1-weighted (TR 600 ms, TE 9.7 ms) image. The tumor mass was enhanced homogeneously except for the spotty signal area of calcification
C
Fig. 3. Time–intensity curve on dynamic Gd-enhanced magnetic resonance study. Note the rapidly ascending slope at the portion from inside the tumor
for diagnosing soft tissue sarcomas in terms of both sensitivity (77%–87%) and specificity(70%–71%) but could not discriminate malignant tumors from benign ones with precision.18,19 Evaluation of the radiological patterns of soft tissue calcification is of great use in the differential diagnosis of soft tissue tumors such as calcifying neurilemoma,
synovial sarcoma, myositis ossificans, tumoral calcinosis, extraskeletal chondroma, extraskeletal osteosarcoma, extraskeletal mesenchymal chondrosarcoma, and ossifying fibromyxoid tumor. Subcutaneous conglomerates of multiple rounded opacities separated by radiolucent lines (fibrous septa) with distinct fluid levels in some of the nodules is typical
604
Y. Miki et al.: Leiomyoma of deep soft tissue
of tumoral calcinosis. Myositis ossificans exhibits a mineralization pattern that appears as a peripheral rim of lamellar bone. Extraskeletal chondromas have ring-like and arc-like calcifications.4 Multiple stippled or small spotty calcifications occur in 15%–20% of synovial sarcomas.20 We were able to differentiate the current lesion from synovial sarcoma by the clinical findings, radiographic pattern of calcification, and decreased signal intensity with iso- to slightly hyperintensity signals on T2-weighted images. Although calcifications in leiomyomas of deep soft tissue are common, the radiological pattern of its calcification has not been well specified. We reviewed 21 reported cases of deep soft tissue leiomyomas located in extremities. Radiological findings were reported in 16 cases, and calcification was found in 70% (12/17) of all
patients on radiography, including those in our study. Radiological findings were described as having a wide variety of aspects, such as linear, mulberry-like, sandlike, and plaque-like calcifications. These suggested no specific form of calcification in leiomyoma of deep soft tissue. In the 21 previously reports that described MRI findings of deep soft tissue leiomyomas in extremities, the signal intensity of the tumors were iso- or lower intensity than surrounding muscles on T1-weighted images in all cases, and 9 cases revealed high intensity on T2weighted images.1–4,6–8,12,14 De Mouy et al. reported signal intensities of T2-weighted images that were high, with areas of signal voids representing calcification.6 Watson et al. reported only one case of leiomyoma of deep soft tissue that showed isointensity on T2-weighted images.
Fig. 4. Fascicular multiplication of spindle cells with oval nuclei. Foci of calcification were prominent in the areas of degenerative change, and a lobular fibrous septum was observed. H&E, ×33
Fig. 6. Dense bodies were frequently observed on microfilaments. Focal pinocytic vesicles and attachment plaque were present underneath the cell membrane. ×5000
A
B Fig. 5. A Positive immunostaining for SMA. ×80 B Immunostaining for CD34 was negative for the tumor cells, but prominent vascularity was identified. ×66
Y. Miki et al.: Leiomyoma of deep soft tissue
They stated that leiomyoma of deep soft tissue should be included in the differential diagnosis of masses that are hypointense on T2-weighted images, such as fibromatosis; and the low signal helps to differentiate the tumor from other calcifying soft tissue masses, such as synovial sarcoma.3 In uterine leiomyoma, variable MRI signal intensities are observed in accordance with variable degrees of degenerative changes, calcification, aseptic necrosis, fibrosis, fatty degeneration, and bleeding.21 In previous reports, cellular areas in uterine leiomyoma could be detected as slightly hyperintense on T2-weighted images.21,22 These findings on T2-weighted MRI uterine leiomyoma images may help in the diagnosis of leiomyoma of deep soft tissue. On the other hand, leiomyoma of deep soft tissue have been reported to be well enhanced, but the patterns of contrast enhancement had not been described on dynamic MRI study. A previous study of uterine leiomyoma using dynamic enhanced MR imaging reported that cellular leiomyomas had marked contrast enhancement during the early phase.18 It stated that evaluation of signal intensity on T2-weighted imaging and the degree of contrast enhancement on dynamic enhanced MR imaging provides useful information for the diagnosis of uterine leiomyoma. In our case, although the tumor was small and arose from a rare site, the MR findings, including the dynamic study, were compatible with uterine leiomyoma. Dynamic MRI study can provide clinically useful information by depicting tissue vascularity and perfusion, capillary permeability, and the composition of the interstitial space; and it enables the prediction of cellular areas of leiomyoma of deep soft tissue. To our knowledge, our study is the first to report correlations between histopathological findings and dynamic MRI studies for leiomyoma of deep soft tissue. We believe that evaluation of radiological patterns of calcification, the signal intensity with T2-weighted imaging, and the patterns of enhancement can assist in an accurate imaging diagnosis of leiomyoma of deep soft tissue.
References 1. Schmidt-Rohlfing B, Tietze L, Siebert CH, Staatz G. Deep softtissue leiomyoma of the popliteal fossa in a 14-year-old girl. Arch Orthop Trauma Surg 2001;121:604–6.
605 2. Misumi S, Irie T, Fukuda K, Tada S, Hosomura Y. A case of deep soft tissue leiomyoma: CT and MRI findings. Radiat Med 2000; 18:253–6. 3. Watson GM, Saifuddin A, Sandison A. Deep soft tissue leiomyoma of the thigh. Skeletal Radiol 1999;28:411–4. 4. Yamato M, Nishimura G, Koguchi Y, Saotome K. Calcified leiomyoma of deep soft tissue in a child. Pediatr Radiol 1999;29: 135–7. 5. Horiuchi K, Yabe H, Mukai M, Morioka H, Udagawa Y, Nozawa S, et al. Multiple smooth muscle tumors arising in deep soft tissue of lower limbs with uterine leiomyomas. Am J Surg Pathol 1998; 22:897–901. 6. De Mouy EH, Kaneko K, Rodriguez RP. Calcified soft tissue leiomyoma of the shoulder mimicking a chondrogenic tumor. Clin Imaging 1995;19:4–7. 7. Lopez-Barea F, Rodriguez-Peralto JL, Burgos E, Gonzalez-Lopez J. Calcified leiomyoma of deep soft tissue: report of a case in childhood. Virchows Arch 1994;425:217–20. 8. Arenas AJ, Urbiola E, Pampliega T, Cordoba A. Deep intramuscular leiomyoma of the lower limb. Acta Orthop Belg 1993;59: 211–3. 9. Goodman AH, Briggs RC. Deep leiomyoma of an extremity. J Bone Joint Surg Am 1965;47:529–32. 10. Bulmer JH. Smooth muscle tumours of the limbs. J Bone Joint Surg Br 1967;49:52–8. 11. Ross LS, Eckstein MR, Hirschhorn R, Khapra AH, Shulman S, Hochstim RJ. Calcified leiomyoma: an unusual cause of large softtissue calcification of calf in childhood. N Y State J Med 1983; 83:747–9. 12. Lubbers PR, Chandra R, Markle BM, Downey EF Jr, Malawer M. Case report 421: calcified leiomyoma of the soft tissues of the right buttock. Skeletal Radiol 1987;16:252–6. 13. Kilpatrick SE, Mentzel T, Fletcher CD. Leiomyoma of deep soft tissue: clinicopathologic analysis of a series. Am J Surg Pathol 1994;18:576–82. 14. Herrlin K, Willen H, Rydholm A. Deep-seated soft tissue leiomyomas: report of four patients. Skeletal Radiol 1990;19:363–5. 15. Abe S, Imamura T, Tateishi A, Park P, Nakano H, Harasawa A, et al. Intramuscular solitary fibrous tumor: a clinicopathological case study. J Comput Assist Tomogr 1999;23:458–62. 16. Tuncbilek N, Karakas HM, Okten OO. Dynamic contrast enhanced MRI in the differential diagnosis of soft tissue tumors. Eur J Radiol 2005;53:500–5. 17. Van Rijswijk CS, Hogendoorn PC, Taminiau AH, Bloem JL. Synovial sarcoma: dynamic contrast-enhanced MR imaging features. Skeletal Radiol 2001;30:25–30. 18. Einarsdottir H, Soderlund V, Skoog L, Bauer HC. Dynamic MRI and fine needle aspiration cytology in the evaluation of soft tissue lesions. Skeletal Radiol 2003;32:695–700. 19. Verstraete KL, Dierick A, De Deene Y, Uyttendaele D, Vandamme F, Roels H, et al. First-pass images of musculoskeletal lesions: a new and useful diagnostic application of dynamic contrast-enhanced MRI. Magn Reson Imaging 1994;12:687–702. 20. Weiss SW, Goldbulm JR. Enzinger and Weiss’s soft tissue tumors. 4th edition. St. Louis: Mosby; 2001. p. 700–4. 21. Yamashita Y, Torashima M, Takahashi M, Tanaka N, Katabuchi H, Miyazaki K, et al. Hyperintense uterine leiomyoma at T2-weighted MR imaging: differentiation with dynamic enhanced MR imaging and clinical implications. Radiology 1993;189:721–5. 22. Hricak H, Tscholakoff D, Heinrichs L, Fisher MR, Dooms GC, Reinhold C, et al. Uterine leiomyomas: correlation of MR, Histopathologic findings, and symptoms. Radiology 1986;158:385–91.
Case report Imaging characteristics of calcified leiomyoma of deep soft tissue YUJI MIKI1, SATOSHI ABE1, TORU TOKIZAKI1, ARIMI HARASAWA2, TETSUO IMAMURA3, and TAKASHI MATSUSHITA1 1 2 3
Department of Orthopaedic Surgery, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan Department of Radiology, Teikyo University School of Medicine, Tokyo, Japan Department of Surgical Pathology, Teikyo University School of Medicine, Tokyo, Japan
Introduction Leiomyoma of the deep soft tissue in the extremities is rare. Only 21 cases have been reported in the literature.1–14 Most of those had developed calcifications, which made the differential diagnosis difficult on imaging. Magnetic resonance imaging (MRI) findings of leiomyoma in the extremities have not been sufficiently documented in conjunction with the differential diagnosis. The purpose of this study was to document the correlation of MRI and histopathological findings of leiomyoma of deep soft tissue in the extremities and to discuss the possibility of reaching an exact imaging diagnosis.
Case report A 14-year-old girl was referred to our hospital for evaluation of a right great toe mass with continuous pain. The mass had been present for approximately 3 years and gradually grew larger. Physical examination revealed an approximately 3-cm, hard, tender mass at the base of the right great toe with an engorged superficial vein. There was no history of trauma, fever, or local heat. Routine laboratory studies were within normal limits. Plain radiographies showed multiple small, patchy calcifications within the tumor mass at the plantar aspect of the first proximal phalanx (Fig. 1). The tumor mass was well circumscribed and essentially isointense to neighboring muscles on T1-weighted MR images. On T2-weighted images, the signal intensity of the tumor was decreased, with isointensity to slightly hyperintensity. Spotty and punctuate signal void lesions were found within the tumor on both T1- and T2-weighted images
Offprint requests to: Y. Miki Received: April 3, 2007 / Accepted: June 28, 2007
(Fig. 2A,B). On Gd-DTPA-enhanced T1-weighted images, the tumor mass was enhanced homogeneously except for spotty low signal areas of calcification (Fig. 2C). The tumor showed marked contrast enhancement during the early phase. Dynamic Gd-enhanced MR study yielded time–intensity curves reflecting rates of gadolinium enhancement ranging from 394% to 546%/ min. A rapidly ascending slope was depicted on the time–intensity curve, which represented rich tumor vessels (Fig. 3). Our clinical diagnosis was benign well-marginated calcified soft tissue tumors including leiomyoma of deep soft tissue, calcifying neurilemoma, myositis ossificans, tumoral calcinosis, extraskeletal chondroma, and ossifying fibromyxoid tumor. The differential diagnoses also included synovial sarcoma, extraskeletal osteosarcoma, and extraskeletal mesenchymal chondrosarcoma. We choose careful excisional biopsy to avoid extensive contamination by incisional or needle biopsy because the tumor mass was small and close to the skin and digital nerves and vessels. Gross findings The tumor was attached to the flexor tendon of the great toe, but there was no adhesion to the skin. It was excised as an en bloc mass with related skin. The tumor was encapsulated, and its mass measured 28 × 25 × 30 mm. On opening the capsule, the tumor surface was grayish-white, and it was nodule-conglomerated with calcified nodules. Microscopic findings Histology of the surgical specimen showed fascicular multiplication of spindle cells with oval nuclei and prominent fascicles suggesting smooth muscle fibers. Foci of the calcification were prominent in the areas of degenerative changes, and hyalinization and a lobular
602
Y. Miki et al.: Leiomyoma of deep soft tissue
Ultrastructural findings The tumor cells were spindle-shaped with spindle- and rather amorphous-shaped nuclei and were surrounded by extracellular matrix consisted of abundant collagen fibers. The cytoplasm contained dense microfilaments, moderate amounts of rough endoplasmic reticulum, small vesicles, mitochondria, and glycogen particles. Dense bodies were frequently observed on microfilaments. Focal pinocytic vesicles and attachment plaques were present underneath the cell membrane. Basal laminae were seen along the cell membrane. These microscopic findings were compatible with leiomyoma (Fig. 6). The tumor was diagnosed as a benign leiomyoma of deep soft tissue. The patient made an uneventful postoperative recovery and was without recurrence 42 months after the surgery. The patient and her family were informed that the data from the case would be submitted for publication and gave their consent.
Discussion
Fig. 1. Radiograph showing multiple small calcifications in the tumor mass
fibrous septum was also observed. The mitotic rate was less than 3 mitotic figures per 50 high-power fields (HPF) without any cellular atypism (Fig. 4). Any correlation between MRI and histopathological findings was studied. Foci of rather decreased signal intensity on T2weighted images were compatible with the areas of degenerative pathological changes of hyalinization, fibrosis, necrosis, and calcification in the tumor. The tumor showed decreased signal intensity with iso- to slightly hyperintensity on T2-weighted images with prominent enhancement following contrast administration in the nonmineralized area of the lesion with moderate cellularity and hypervascularity. Immunohistochemical findings Vimentin (Dako, Glostrup, Denmark), SMA (Dako), and desmin (Dako) was found the cytoplasm of the spindle tumor cells. Immunoreactivity of CD-34 (Dako) was negative for tumor cells, but prominent vascularity was identified (Fig. 5A,B).
We compared histological and imaging findings. The tumor mass included multiple small calcifications in the soft tissue mass on plain radiography and spotty and punctuate signal void lesions on MRI. These lesions represented prominent foci of stromal dystrophic calcification on histological examination. The MR findings revealed the tumor mass to be essentially isointense to muscle on T1-weighted images and to have decreased signal intensity with iso- to relatively high intensity on T2-weighted images. The tumor showed prominent enhancement following contrast administration in the nonmineralized area with moderate cellularity and hypervascularity. Dynamic MR study depicted a rapidly ascending slope followed by a gradually descending slope. This type of time–intensity curve correlated with vascular and cellular lesions on histological examination.15 These imaging findings represented histological features of cellular areas with hypervascularity and coexisting regressive changes. In a comparison between malignant and benign soft tissue tumors that were operated on and had a dynamic MR imaging study, both enhancement during the early and late phases were higher in malignant tumors. However, some benign tumors, such as hemangioma, myositis ossificans, and aggressive fibromatosis, may show high contrast enhancement.16 The distinctive enhanced MR imaging characteristics in a synovial sarcoma revealed an early start of enhancement, peripheral tumoral enhancement, and rapid initial enhancement followed by a plateau or washout phase.17 Dynamic MR findings were valuable
Y. Miki et al.: Leiomyoma of deep soft tissue
603
B
A
Fig. 2. A T1-weighted (TR 600 ms, TE 9.7 ms) image. The tumor mass is isointense to the muscle with spotty signal voids. B T2-weighted (TR 3000 ms, TE 86.5 ms) image. The signal intensity of the tumor showed decreased signal intensity with iso- to relatively high intensity. C Gadoliniumdiethylenetriamine pentaacetic acid (Gd-DTPA)-enhanced T1-weighted (TR 600 ms, TE 9.7 ms) image. The tumor mass was enhanced homogeneously except for the spotty signal area of calcification
C
Fig. 3. Time–intensity curve on dynamic Gd-enhanced magnetic resonance study. Note the rapidly ascending slope at the portion from inside the tumor
for diagnosing soft tissue sarcomas in terms of both sensitivity (77%–87%) and specificity(70%–71%) but could not discriminate malignant tumors from benign ones with precision.18,19 Evaluation of the radiological patterns of soft tissue calcification is of great use in the differential diagnosis of soft tissue tumors such as calcifying neurilemoma,
synovial sarcoma, myositis ossificans, tumoral calcinosis, extraskeletal chondroma, extraskeletal osteosarcoma, extraskeletal mesenchymal chondrosarcoma, and ossifying fibromyxoid tumor. Subcutaneous conglomerates of multiple rounded opacities separated by radiolucent lines (fibrous septa) with distinct fluid levels in some of the nodules is typical
604
Y. Miki et al.: Leiomyoma of deep soft tissue
of tumoral calcinosis. Myositis ossificans exhibits a mineralization pattern that appears as a peripheral rim of lamellar bone. Extraskeletal chondromas have ring-like and arc-like calcifications.4 Multiple stippled or small spotty calcifications occur in 15%–20% of synovial sarcomas.20 We were able to differentiate the current lesion from synovial sarcoma by the clinical findings, radiographic pattern of calcification, and decreased signal intensity with iso- to slightly hyperintensity signals on T2-weighted images. Although calcifications in leiomyomas of deep soft tissue are common, the radiological pattern of its calcification has not been well specified. We reviewed 21 reported cases of deep soft tissue leiomyomas located in extremities. Radiological findings were reported in 16 cases, and calcification was found in 70% (12/17) of all
patients on radiography, including those in our study. Radiological findings were described as having a wide variety of aspects, such as linear, mulberry-like, sandlike, and plaque-like calcifications. These suggested no specific form of calcification in leiomyoma of deep soft tissue. In the 21 previously reports that described MRI findings of deep soft tissue leiomyomas in extremities, the signal intensity of the tumors were iso- or lower intensity than surrounding muscles on T1-weighted images in all cases, and 9 cases revealed high intensity on T2weighted images.1–4,6–8,12,14 De Mouy et al. reported signal intensities of T2-weighted images that were high, with areas of signal voids representing calcification.6 Watson et al. reported only one case of leiomyoma of deep soft tissue that showed isointensity on T2-weighted images.
Fig. 4. Fascicular multiplication of spindle cells with oval nuclei. Foci of calcification were prominent in the areas of degenerative change, and a lobular fibrous septum was observed. H&E, ×33
Fig. 6. Dense bodies were frequently observed on microfilaments. Focal pinocytic vesicles and attachment plaque were present underneath the cell membrane. ×5000
A
B Fig. 5. A Positive immunostaining for SMA. ×80 B Immunostaining for CD34 was negative for the tumor cells, but prominent vascularity was identified. ×66
Y. Miki et al.: Leiomyoma of deep soft tissue
They stated that leiomyoma of deep soft tissue should be included in the differential diagnosis of masses that are hypointense on T2-weighted images, such as fibromatosis; and the low signal helps to differentiate the tumor from other calcifying soft tissue masses, such as synovial sarcoma.3 In uterine leiomyoma, variable MRI signal intensities are observed in accordance with variable degrees of degenerative changes, calcification, aseptic necrosis, fibrosis, fatty degeneration, and bleeding.21 In previous reports, cellular areas in uterine leiomyoma could be detected as slightly hyperintense on T2-weighted images.21,22 These findings on T2-weighted MRI uterine leiomyoma images may help in the diagnosis of leiomyoma of deep soft tissue. On the other hand, leiomyoma of deep soft tissue have been reported to be well enhanced, but the patterns of contrast enhancement had not been described on dynamic MRI study. A previous study of uterine leiomyoma using dynamic enhanced MR imaging reported that cellular leiomyomas had marked contrast enhancement during the early phase.18 It stated that evaluation of signal intensity on T2-weighted imaging and the degree of contrast enhancement on dynamic enhanced MR imaging provides useful information for the diagnosis of uterine leiomyoma. In our case, although the tumor was small and arose from a rare site, the MR findings, including the dynamic study, were compatible with uterine leiomyoma. Dynamic MRI study can provide clinically useful information by depicting tissue vascularity and perfusion, capillary permeability, and the composition of the interstitial space; and it enables the prediction of cellular areas of leiomyoma of deep soft tissue. To our knowledge, our study is the first to report correlations between histopathological findings and dynamic MRI studies for leiomyoma of deep soft tissue. We believe that evaluation of radiological patterns of calcification, the signal intensity with T2-weighted imaging, and the patterns of enhancement can assist in an accurate imaging diagnosis of leiomyoma of deep soft tissue.
References 1. Schmidt-Rohlfing B, Tietze L, Siebert CH, Staatz G. Deep softtissue leiomyoma of the popliteal fossa in a 14-year-old girl. Arch Orthop Trauma Surg 2001;121:604–6.
605 2. Misumi S, Irie T, Fukuda K, Tada S, Hosomura Y. A case of deep soft tissue leiomyoma: CT and MRI findings. Radiat Med 2000; 18:253–6. 3. Watson GM, Saifuddin A, Sandison A. Deep soft tissue leiomyoma of the thigh. Skeletal Radiol 1999;28:411–4. 4. Yamato M, Nishimura G, Koguchi Y, Saotome K. Calcified leiomyoma of deep soft tissue in a child. Pediatr Radiol 1999;29: 135–7. 5. Horiuchi K, Yabe H, Mukai M, Morioka H, Udagawa Y, Nozawa S, et al. Multiple smooth muscle tumors arising in deep soft tissue of lower limbs with uterine leiomyomas. Am J Surg Pathol 1998; 22:897–901. 6. De Mouy EH, Kaneko K, Rodriguez RP. Calcified soft tissue leiomyoma of the shoulder mimicking a chondrogenic tumor. Clin Imaging 1995;19:4–7. 7. Lopez-Barea F, Rodriguez-Peralto JL, Burgos E, Gonzalez-Lopez J. Calcified leiomyoma of deep soft tissue: report of a case in childhood. Virchows Arch 1994;425:217–20. 8. Arenas AJ, Urbiola E, Pampliega T, Cordoba A. Deep intramuscular leiomyoma of the lower limb. Acta Orthop Belg 1993;59: 211–3. 9. Goodman AH, Briggs RC. Deep leiomyoma of an extremity. J Bone Joint Surg Am 1965;47:529–32. 10. Bulmer JH. Smooth muscle tumours of the limbs. J Bone Joint Surg Br 1967;49:52–8. 11. Ross LS, Eckstein MR, Hirschhorn R, Khapra AH, Shulman S, Hochstim RJ. Calcified leiomyoma: an unusual cause of large softtissue calcification of calf in childhood. N Y State J Med 1983; 83:747–9. 12. Lubbers PR, Chandra R, Markle BM, Downey EF Jr, Malawer M. Case report 421: calcified leiomyoma of the soft tissues of the right buttock. Skeletal Radiol 1987;16:252–6. 13. Kilpatrick SE, Mentzel T, Fletcher CD. Leiomyoma of deep soft tissue: clinicopathologic analysis of a series. Am J Surg Pathol 1994;18:576–82. 14. Herrlin K, Willen H, Rydholm A. Deep-seated soft tissue leiomyomas: report of four patients. Skeletal Radiol 1990;19:363–5. 15. Abe S, Imamura T, Tateishi A, Park P, Nakano H, Harasawa A, et al. Intramuscular solitary fibrous tumor: a clinicopathological case study. J Comput Assist Tomogr 1999;23:458–62. 16. Tuncbilek N, Karakas HM, Okten OO. Dynamic contrast enhanced MRI in the differential diagnosis of soft tissue tumors. Eur J Radiol 2005;53:500–5. 17. Van Rijswijk CS, Hogendoorn PC, Taminiau AH, Bloem JL. Synovial sarcoma: dynamic contrast-enhanced MR imaging features. Skeletal Radiol 2001;30:25–30. 18. Einarsdottir H, Soderlund V, Skoog L, Bauer HC. Dynamic MRI and fine needle aspiration cytology in the evaluation of soft tissue lesions. Skeletal Radiol 2003;32:695–700. 19. Verstraete KL, Dierick A, De Deene Y, Uyttendaele D, Vandamme F, Roels H, et al. First-pass images of musculoskeletal lesions: a new and useful diagnostic application of dynamic contrast-enhanced MRI. Magn Reson Imaging 1994;12:687–702. 20. Weiss SW, Goldbulm JR. Enzinger and Weiss’s soft tissue tumors. 4th edition. St. Louis: Mosby; 2001. p. 700–4. 21. Yamashita Y, Torashima M, Takahashi M, Tanaka N, Katabuchi H, Miyazaki K, et al. Hyperintense uterine leiomyoma at T2-weighted MR imaging: differentiation with dynamic enhanced MR imaging and clinical implications. Radiology 1993;189:721–5. 22. Hricak H, Tscholakoff D, Heinrichs L, Fisher MR, Dooms GC, Reinhold C, et al. Uterine leiomyomas: correlation of MR, Histopathologic findings, and symptoms. Radiology 1986;158:385–91.