Alveolar soft part sarcoma
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| Alveolar soft part sarcoma | |
|---|---|
| Diagnosis in short | |
 ASPS. H&E stain. | |
|
| |
| LM | large cells (~30-50 μm) with abundant eosinophilic cytoplasm and an eccentric nucleus +/-nucleolus, arranged in nest/separated by thin septa - vaguely resembles alveoli (at low power) |
| LM DDx | alveolar rhabdomyosarcoma |
| Stains | PAS +ve (cytoplasm) |
| IHC | TFE3 +ve (suggestive of translocation) |
| Molecular | t(X;17) |
| Site | soft tissue - usu. head and neck |
|
| |
| Prognosis | poor |
Alveolar soft part sarcoma, abbreviated ASPS, is a rare malignant soft tissue lesion typically seen in younger individuals.
General
- Adolescents/young adults.
- Children -- classically location: base of tongue and orbit.
- Typical indolent initially - ultimately a poor prognosis.[1]
Microscopic
Features:[2]
- Arranged in nest/separated by thin septa; vaguely resembles alveoli (at low power).
- Large cells (~30-50 μm) with abundant eosinophilic cytoplasm.
- An eccentric nucleus.
- +/-Nucleolus.
DDx:
- Rhabdomyosarcoma, alveolar - usu. does not have sheets of rhabdoid cells.
Images
ASPS - low mag. (WC/Nephron)
ASPS - intermed. mag. (WC/Nephron)
ASPS - very high mag. (WC/Nephron)
www:
Stains
- PAS +ve (cytoplasmic) - considered the most useful.[3]
- PASD +ve (cytoplasmic).
IHC
- TFE3 +ve -- suggestive of characteristic translocation.
- Desmin ~ 50% of cases.
Others:
- EMA -ve.
- Cytokeratins -ve.
- HMB45 -ve.
- Melan‐A -ve.
Molecular
- t(X;17)(p11.2;q25).[4]
Note:
- Same translocation may be seen in renal tumour with Xp11.2 translocation.
EM
- Distinctive membrane-bound intracytoplasmic crystal lattice with ~5 nm fibres spaced 10 nm apart.[1]
Image:
See also
References
- ↑ 1.0 1.1 1.2 Folpe, AL.; Deyrup, AT. (Nov 2006). "Alveolar soft-part sarcoma: a review and update.". J Clin Pathol 59 (11): 1127-32. doi:10.1136/jcp.2005.031120. PMC 1860509. PMID 17071801. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1860509/.
- ↑ Humphrey, Peter A; Dehner, Louis P; Pfeifer, John D (2008). The Washington Manual of Surgical Pathology (1st ed.). Lippincott Williams & Wilkins. pp. 627. ISBN 978-0781765275.
- ↑ Zarrin-Khameh, N.; Kaye, KS. (Mar 2007). "Alveolar soft part sarcoma.". Arch Pathol Lab Med 131 (3): 488-91. doi:10.1043/1543-2165(2007)131[488:ASPS]2.0.CO;2. PMID 17516754.
- ↑ Online 'Mendelian Inheritance in Man' (OMIM) 606243