Alveolar soft part sarcoma: a rare diagnosis.

Alveolar soft-part sarcoma (ASPS) is an extremely rare disease arising from connective tissues with a propensity for recurrence and metastasis. Clinically, it can be confused with hemangioma or arterio-venous malformations. Thus, a high index of suspicion and histopathological examination are required to make a definitive diagnosis. We report a case of recurrent ASPS in a young female with multiple sites involvement without any features of metastasis who has been treated with excision of the symptomatic lesions followed by chemotherapy.

What was known?

Alveolar soft part sarcoma is a rare type of soft tissue sarcoma affecting female more than male and clinically mimics hemangioma or arterio-venous malformation.

Introduction

Alveolar soft-part sarcoma (ASPS) is an extremely rare disease arising from connective tissues. ASPS predominately affects adolescents and young adults with a predilection for women.[1] It occurs commonly in the lower extremities (44%) and the head and neck (27%), of which 25% occur in the tongue.[2] Although the origin of ASPS is still unknown, recent cytogenetic studies revealed some chromosomal translocation, which may have a role.[3] The tumor runs an indolent course, but may recur and metastasize, leading to high mortality. We describe such a rare case.

Case Report

A 32-years-old female from a remote village presented with multiple painless soft globular swellings all over the body including face, tongue, neck, chest, abdomen, back, genitalia, and all the limbs for a duration of 3 months [Figures 1 and 2]. Most of the lesions were skin-colored, but few of the lesions over forehead, neck, back, and genitalia showed reddish to bluish discoloration while few showed crusting over the surface. The patient gave history of similar type of lesion in right thigh 3 years back, for which she underwent surgical excision, but no histopathological examination, was done at that time. There was associated history of anorexia, weight loss, and fatigue. On examination, apart from the aforesaid lesions, a nodule was palpable in the posterior fornix of vagina and another in the anterior rectal wall 6 cm from anal verge. Other systems were within normal limit. After thorough investigations, all the blood parameters were found to be normal, except moderate degree of anemia. Fortunately, her chest X-ray, USG of whole abdomen, CT scan of brain revealed no abnormality. The most symptomatic swelling which were present over right thigh (at the site of previous excision) and back were excised followed by biopsy. Histopathology showed large polygonal cells with eccentrically-placed prominent nucleus and abundant eosinophilic cytoplasm arranged in an alveolar pattern separated by fibrous septae and occasional mitotic figures [Figure 3]. Cytopathology revealed the tumors cells expressing vimentin. Following surgery, the patient was referred to radiotherapy department and was put on chemotherapy regimen comprising of vincristine (2 mg), adriamycin (60 mg), and cyclophosphamide (90 mg), given at an interval of 3 weeks. She received 6 such cycles and is under close follow-up. There is mild reduction of the lesions with moderate symptomatic improvement and without any features of metastasis.

Figure 1

Multiple globular swellings over the back of trunk

Figure 2

Similar swellings over face and neck

Figure 3

Characterisistic histopathology of ASPS

Discussion

ASPS was first described by Christopherson, et al. in 1952.[4] ASPS comprises only 1% of all soft tissue sarcomas.[2] The tumor occurs most commonly in the soft tissues of the extremities, rarely in arm, chest, and retro-peritoneal tissues, even stomach and female genital tract has been reported.[56] The tumor occurs predominantly in females, with a male:female ratio of 1:2.[1] The most probable genetic theory of origin is chromosomal re-arrangements at t (X;17)(p11;q25), resulting in the ASPL-TFE3 fusion gene.[3] Since women have an extra X-chromosome, they are likely to develop an X autosomal translocation, which is theoretically doubles that of men.[3] ASPS have a close clinical resemblance to hemangioma. Histo-pathologically, ASPS needs to be differentiated from paraganglioma, rhabdomyosarcoma, metastatic adrenal carcinoma and melanoma by demonstrating cytological uniformity, lack of nuclear atypia, and paucity of mitotic figures in ASPS. The outcomes depend on prognostic factors such as a patient's age, tumor size, recurrence (which has been reported to range from 11-50%[7] ), and the presence of metastasis at the time of diagnosis. It usually metastasizes late to the lungs, bones, lymph nodes, and brain.[78] Accurate diagnosis and treatment of this unusual tumor requires clinical suspicion and clinico-pathological correlation with appropriate radiological studies. Wide excision is the therapy of choice for localized disease.[9] While surgery may improve outcomes, traditional chemotherapeutic agents and/or radiotherapy have limited role.[10] As treatment options are limited when lesions are multiple, surgical resection of the symptomatic lesions followed by chemotherapy was given in our patient. In spite of extensive involvement, metastasis did not occur in this patient till her last visit.

Conclusion

ASPS is a rare tumor. To the best of our knowledge, very few cases of ASPS has been reported from India. Moreover, this female with multiple lesions involving unusual sites but without any features of metastasis is uncommon of ASPS. However, a classical histopathological feature from the biopsy of the lesions favors the diagnosis. Because of the rarity of occurrence of the tumor with uncommon presentation, the case has been reported.

What is new?

1. Occurrence of multiple lesions in ASPS, astonishingly without any metastasis in the present case.

2. When lesions are multiple, surgical excision of the symptomatic lesions followed by chemotherapy is a good treatment option.