LETTER TO EDITOR
Year : 2001 | Volume
: 11 | Issue : 1 | Page : 44--45
Alveolar soft part sarcoma with cerebral and skeletal metastases
A Prasad, BKS Chauhan, HK Pal, M Bhardwaj
Department of Radiology, Neurosurgery and Pathology, RML Hospital, New Delhi, India
Department of Radiology, Neurosurgery and Pathology, RML Hospital, New Delhi
|How to cite this article:|
Prasad A, Chauhan B, Pal H K, Bhardwaj M. Alveolar soft part sarcoma with cerebral and skeletal metastases.Indian J Radiol Imaging 2001;11:44-45
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Prasad A, Chauhan B, Pal H K, Bhardwaj M. Alveolar soft part sarcoma with cerebral and skeletal metastases. Indian J Radiol Imaging [serial online] 2001 [cited 2020 Jun 5 ];11:44-45
Available from: http://www.ijri.org/text.asp?2001/11/1/44/28314
Alveolar soft part Sarcoma (ASPS) is a rare soft tissue tumor. Most frequently it is seen in young adults, presenting as a slow growing mass. It is known to metastasize to lungs, brain and bones. The cell of origin is still controversial but the arrangement of cells on histopathology resembles that of an alveolar pattern and hence the name. Imaging is of considerable importance for pre-operative localization and long term surveillance of this slow growing but invariably disseminating tumor.
A twenty-six-years old man presented with features suggestive of acute onset of lower cranial nerve palsies (involving IX, X & XI cranial nerves) resulting in dyspnea, hoarseness of voice and dysphagia, for 10 days. He gave a history of multiple slow growing soft tissue swellings in his left groin, extending to the thigh, present for the last 8 to 10 years and a similar swelling in the left leg for the last three years. A local examination revealed multiple subcutaneous swellings in the left groin, left calf and ankle, which were firm, non-tender and with no changes in the overlying skin. A CNS examination revealed palsy of the lower cranial nerves (IX, X, XI).
A radiograph of the left leg revealed an increase in soft tissue density with no evidence of bone destruction or calcification. Contrast enhanced CT of the abdomen and pelvis revealed a large dumb-bell shaped soft tissue mass partly in the pelvis, indenting the urinary bladder, stretching and displacing the left ureter, partly coming out of the inguinal compartment, antero-medial to the vessels and extending to the thigh. The mass showed intense heterogenous enhancement, more in the periphery with central necrotic areas [Figure 1]. There was a separate focal right pedicular destruction of the T-11 vertebra along with a small hyperdense extradural mass indenting the thecal compartment on the right side. The CECT head revealed bilateral large cerebello-pontine (CP) angle masses with intense patchy enhancement and evidence of bone destruction involving the right petrous bone, left lip of foramen magnum and left atlanto-occipital joint. MRI with high resolution T1W and T2W images revealed similar findings [Figure 2],[Figure 3] with extension to the lateral medullary cistern on the left side. The mass on the right extended superiorly into the middle cranial fossa to abut the medial pole of the right temporal lobe and Meckel's cave, displacing the internal carotid artery. Inferiorly both masses extended through their respective jugular foramina into the retropharyngeal and parapharyngeal spaces. Both the masses appeared isointense to grey matter on T1W and T2W images and showed central cystic degenerative changes. Debulking of the left CP angle mass was performed through a left sub-occipital craniectomy. The left ankle and popliteal masses were also excised and histopathology revealed an alveolar soft part Sarcoma
Soft tissue sarcomas account for one per cent of all malignant neoplasms and ASPS accounts for less than one per cent of soft tissue sarcomas . Described as a discrete clinical entity by Smetana and Scott , its histogenesis is still unknown. It got its name due to its superficial resemblance to an alveolus, most significant morphological features being organoid pattern and ultrastructural demonstration of secretory activity resulting in formation of characteristic PAS positive crystals. More recently, a skeletal muscle origin has been proposed. It occurs in the second to fourth decade of life with a female preponderance and the most common sites of involvement are the lower extremities, head and neck, upper extremity and trunk in decreasing order ,. Radiologically it presents as a nonspecific soft tissue mass that may involve a long segment of soft tissue of the extremity with possible involvement of the underlying bone. CT findings are that of a low attenuating soft tissue mass vigorously enhancing after contrast with enlarged vessels. . Bone erosion and poor margination of the tumor have been described (seen in our case) probably commensurate with incomplete encapsulation seen on histopathology of many ASPS tumors.
The MR appearance of ASPS have been reviewed by a few studies in the past , which conclude that though most soft tissue sarcomas are isointense to muscle, most ASPS demonstrate high signal intensity on both T1W and T2W images with flow voids in the core and margins of tumors. These are the characteristic MR findings that may lead to early diagnosis in appropriate clinical settings, but in our case the lesion was isointense on T1W and T2W images. Metastases to the brain and skeleton are the second most common sites, the lungs being the first. The incidence of metastases has been reported to be between 30 and 46 per cent . The most interesting part of this rare tumor is that there can be a median time of six years before the appearance of the first metastasis and that 38 per cent of metastases occur 10 years after the diagnosis.
In conclusion it can be said that ASPS is still a puzzle with respect to its histogenesis. It is a slow growing tumor with propensity to metastasize after a long interval. Hence it may be considered as a differential diagnosis in a young adult with slow growing hypervascular soft tissue masses, especially with characteristic MR features.
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