Standford school of Medicine-Alveolar Soft Part Sarcoma

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Alveolar Soft Part Sarcoma
Definition

“Sarcoma with large poorly cohesive cells with distinctive regular alveolar pattern
Diagnostic Criteria

Large poorly cohesive round cells in nests
Nodular growth pattern
Composed of small nests or packets
At least focally, sometimes completely
25-50 cells per nest in cross-section on average
May vary from single cells to large numbers of cells
Peripheral layer of cells frequently adheres to surrounding septum
Rarely spindled or pseudoglandular pattern
Nests surrounded by thin walled vessels rather than connective tissue
May produce sinusoidal pattern
Cytoplasm abundant, granular, eosinophilic
Crystals reported in up to 80% of cases
Rod shaped
PAS positive, diastase resistant
May be irregular
Glycogen usually present at least focally
PAS positive, diastase sensitive
May have vacuoles
May be clumped with clear areas
May form globular inclusions
Nuclei large, regular, round and vesicular
Nucleoli prominent
Pleomorphism may be focal but not widespread
Mitotic figures rare
Multinucleated cells may be present
Vascular invasion frequent
Richard L Kempson MD
Robert V Rouse MD rouse@stanford.edu
Department of Pathology
Stanford University School of Medicine
Stanford CA 94305-5342

Original posting/updates:: 7/19/07, 8/4/10

Supplemental studies

Immunohistology

Muscle markers
TFE3 100% positive
Desmin About 50% positive
Muscle specific actin Variable, occasional cases positive
Smooth muscle actin Variable, occasional cases positive
Myoglobin Variable, occasional cases positive
MyoD1 All recent reports negative
S100 variable, occasional cases positive
HMB45 negative
Keratin negative
Chromogranin 1/5 positive
TFE3 also stains Xp11 translocation renal cell carcinoma
Focal and less intense reactions seen in melanoma, clear cell sarcoma, PEComa and angiomyolipoma
Genetic analysis

Unbalanced translocation der(17)t(X;17)(p11.2;q25) present in all cases studied, produces TFE3-ASPL gene product.
Detectable with two color break-apart FISH
Identical fusion transcript resulting from a balanced translocation is found in translocation-associated renal carcinomas.
Differential Diagnosis

Alveolar rhabdomyosarcoma
Metastatic carcinoma
Metastatic melanoma
Granular cell tumor
Paraganglioma
Alveolar rhabdomyosarcoma Alveolar Soft Part Sarcoma
Variably shaped alveolar spaces Regular alveolar spaces
Fibrous septa around nests Thin walled vascular septa
Cells generally 10-30 microns diameter Cells larger
Pleomorphic nuclei Only mild pleomorphism
Dense nuclei Vesicular nuclei
Small nucleoli Prominent nucleoli
No crystals Crystals in up to 80% of cases
Uniformly desmin, actin positive Occasionally desmin, actin positive
Frequently MyoD1 positive MyoD1 rare or negative
Translocations t(2;13) or t(1;13) der(17)t(X;17)(p11.2;q25)


Granular cytoplasm and / or nesting pattern of cells in the following may raise the question of alveolar soft part sarcoma

Metastatic Carcinoma Alveolar Soft Part Sarcoma
Keratin positive Keratin negative
Desmin, actin negative Occasionally desmin, actin positive
May have pleomorphic nuclei Only mild pleomorphism
Unusual in young adults Usually young adults
Morphologically similar carcinomas include renal cell and ovarian clear cell


Metastatic melanoma Alveolar Soft Part Sarcoma
Uniformly S100 positive S100 variable
HMB45 85% positive HMB45 negative
Desmin, actin negative Occasionally desmin, actin positive
Pleomorphic nuclei Only mild pleomorphism
Unusual in young adults Usually young adults


Granular Cell Tumor Alveolar Soft Part Sarcoma
Uniformly S100 positive S100 variable
No regular nests of cells Regular nests of cells
Dense granular cytoplasm Variable granularity, frequent vacuoles


Paraganglioma Alveolar Soft Part Sarcoma
Usually small nests (zellballen) Usually large nests
Surrounded by fibrous tissue Surrounded by thin walled vessels
Small to medium size cells Large cells
Dense nuclei, often spiculated chromatin Vesicular nuclei
Inconspicuous nucleoli Prominent nucleoli
Chromogranin positive One case reported chromogranin positive
S100 sustentacular cells frequent No sustentacular cells
Desmin, actin negative Occasionally desmin, actin positive
Does not occur on extremities Frequently involves extremities
Clinical

Age range 2-70 years, most are 15-35 years
Location
60% extremities (frequently thigh)
20% trunk
12% head and neck
8% retroperitoneum
Unusual sites include oral cavity, uterus
Over half present with metastases
Frequent metastatic sites lung and brain
Primary may be occult
Metastasis and death may occur late (>10 years), even if clearly excised with no local recurrence
5 year survival 60% but 20 year survival 15%
Pediatric cases may have better survival
Grading / Staging / Report

According to the guidelines of the ADASP, alveolar soft part sarcoma is not considered gradable although it often metastasizes

French Federation of Cancer Centers System grading scheme for adult sarcomas

Tumor differentiation score = 3 for alveolar soft part sarcoma
Mitotic index
Score 1 0-9 mitoses per 10 hpf (0.1744 sq mm)
Score 2 10-19 mitoses per 10 hpf
Score 3 >19 mitoses per 10 hpf
Tumor cell necrosis
Score 0 No necrosis on any slide (one slide per 2 cm tumor diameter)
Score 1 <50% of tumor is necrotic on slides examined
Score 2 >50% of tumor is necrotic on slides examined
Final Grade (add the three scores above)
Grade 1 Sum of scores = 2 or 3
Grade 2 Sum of scores = 4 or 5
Grade 3 Sum of scores = 6 or more
Use TNM Staging

The surgical pathology report should contain or address the following:

Location
Type of resection or biopsy
Histologic diagnosis
Managerial category IV (Systemic disease assumed to be present at the outset)
Extent of tumor cell necrosis
Size
Depth (dermis, subcutis, below fascia, body cavity)
Margins
Involved
Not involved
If under 2 cm give all such distances and sites
If over 2 cm give minimum distance and site
Results of supplementary studies if performed
Relationship to other specimens from the same patient“


http://surgpathcriteria.stanford.edu/so ... table.html

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TNM staging system listen (… STAY-jing SIS-tem)
A system to describe the amount and spread of cancer in a patient’s body, using TNM. T describes the size of the tumor and any spread of cancer into nearby tissue; N describes spread of cancer to nearby lymph nodes; and M describes metastasis (spread of cancer to other parts of the body). This system was created and is updated by the American Joint Committee on Cancer (AJCC) and the International Union Against Cancer (UICC). The TNM staging system is used to describe most types of cancer. Also called AJCC staging system.

https://www.cancer.gov/publications/dic ... ing-system