Metastatic alveolar soft tissue sarcoma

Case contributed by Dr Hazem M Almasarei

Presentation

Adult male with no past medical history presented with left leg pain.

Patient Data

Age: 30 years
Gender: Male
X-ray

Left leg

There are two lytic lesions involving the midshaft/diaphysis of the left tibia. They are relatively well-defined. There is a narrow zone of transition. There is no definite soft tissue component. There is no bony expansion. There is no periosteal reaction.

CT

Left leg

There are two cortical lytic lesions, involving the anterior aspect of the left tibia. The largest one associated with a small soft tissue component. Regarding the mass, it appears isodense and barely seen.

MRI

Left leg

There is a relatively well defined lobulated hypervascular soft tissue mass lesion within the leg mainly centered at the soleus muscle. There are two cortical bony lesions involving the left tibia. 

T1: The mass appears slightly hyperintense.

T2: The mass is hyperintense and associated with multiple vascular signal voids.

DSA (angiography)

Left leg

Interventional catheter angiogram showing a highly vascular lesion in the calf of the left leg. There is enlargement of the arteries and abnormal connections between the arteries and veins, representing an arteriovenous malformation. Tumor-induced angiogenesis and two vascular supply the tibial surface with a vascular blush, representing metastatic deposits.

Nuclear medicine

Lower limbs

Hypermetabolic FDG was avid in the left tibial bone lesion with cortical destruction and a surrounding soft tissue component.

X-ray

Chest

Innumerable variable sized and shaped bilateral pulmonary nodules giving the appearance of cannonballs, representing pulmonary metastases.

CT

Chest

There are bilateral innumerable variable in sized and shaped bilateral pulmonary nodules, in keeping with the pulmonary metastases.

MRI

Brain

Multiple intra-axial homogeneous enhancing lesions, in the right temporoparietal lobes, mainly in the white-grey matter interface, compatible with parenchymal brain metastases.

Pathology

Gross Description: The specimen was taken from the lung and received in formalin. It consists of multiple cores; the longest measuring 1.2 cm. All submitted in one block.

Microscopic: PAS-positive, diastase-resistant, intracytoplasmic crystals and granules and intracytoplasmic glycogen are present to variable degrees. Nuclear pleomorphism is usually mild and mitotic activity low. Vascular invasion is identified in nearly all cases.

Immunohistochemistry Profile: TFE3: strong and diffuse nuclear positivity. PAS (special stain): positive for intracytoplasmic structures. S100, Pan CK, CK-MNF, CK 8/18, Inhibin, HEPBAR, HMB45, EMA, lysozyme, and PAX-8: Negative.

Differential Diagnosis:

  • metastatic clear cell renal cell carcinoma is positive for EMA, CD10, and RCC and negative for TFE3
  • melanoma is positive for S-100, HMB-45 and melan-A
  • paraganglioma is positive for chromogranin and Synaptophysin
  • granular cell tumor is positive for S–100
  • clear cell sarcoma is positive for S-100, HMB-45, and melan–A

Diagnosis: Alveolar soft tissue sarcoma

Case Discussion

Alveolar soft part sarcoma (ASPS) is a rare and slow-growing soft tissue malignant tumor and accounts for less than 1% (0.5–0.9%) of all soft tissue sarcomas.

It occurs at any age but mostly occurs in adolescent and young adults with a female predominance. The most common involved site in adults is the lower extremities, while in children the head and neck are the most often involved.

Most of the patients presented with metastatic deposits to the lung, brain and bone. Metastasis may occur after tumor resection, despite the absence of local recurrence. Alveolar soft-part sarcoma has a poor prognosis.

Diagnosis of alveolar soft part sarcoma based on histopathology, immunohistochemistry and molecular features.

The crucial treatment for alveolar soft part sarcoma is complete surgical resection with a safe margin. Radiotherapy and chemotherapy are also used for treatment. However, the latter shows resistant to an adult patient.

 

Acknowledgements for additional contributor:

Dr. Loay Emad Abudalu, Histopathology clinical fellow Sheffield Children’s Hosptial Sheffield-UK.

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Case information

rID: 56707
Published: 27th Aug 2019
Last edited: 28th Aug 2019
Inclusion in quiz mode: Included
Institution: King Hussein Cancer Center

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