Unexpected Immunoreactivity in Soft Tissue Tumors: Often Confusing, Occasionally Helpful, and Sometimes Just Plain Odd No Disclosures
3/23/2017
Unexpected Immunoreactivity in Soft Tissue Tumors: Often Confusing, Occasionally Helpful, and Sometimes Just Plain Odd No Disclosures
Andrew L. Folpe, MD Mayo Clinic, Rochester MN [email protected]
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Unexpected Immunoreactivity in Soft Tissue Tumors • Intermediate filaments • Neuroendocrine markers • Miscellaneous Aberrant Patterns of Intermediate Filament and Neuroendocrine Marker Expression Which Seem to Exist Only to Torture Surgical Pathologists
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Intermediate Filaments: The Good Old Days • Cytokeratins • Glial fibrillary acidic protein • Carcinomas • Gliomas • Vimentin • Desmin • Sarcomas • Myogenous tumors • Neurofilaments • Minor intermediate filaments • Neural tumors
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Keratin
Keratin
Sarcomatoid SCC Vimentin ©2016 MFMER | slide-7 ©2016 MFMER | slide-8
CK7
Leiomyosarcoma Keratin ©2016 MFMER | slide-9 ©2016 MFMER | slide-10
Keratin
Keratin expression in 20% of studied ES/PNET
Keratin
Epithelioid AS CD31 ©2016 MFMER | slide-11 ©2016 MFMER | slide-12
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CK Keratin
Keratin expression in 32% of cases; desmin expression in 2%
GFAP Desmin
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S100 protein • Cytokeratin expression in 50% • Expression of at least one NE marker in 43% • Synaptophysin expression in 32% • Chromogranin A expression in 22% • Synaptophysin and chromogranin A expression in 11%
SOX10 Desmin
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• Keratin: 30-40% Desmin Myogenin • Desmin: 24% • NF: 16% • Synapto: 29%
S100 Synapto
Keratin SYN ©2016 MFMER | slide-17 ©2016 MFMER | slide-18
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Melanoma S100 protein S100 protein
CK Melan A Desmin HMB45 ©2016 MFMER | slide-19 ©2016 MFMER | slide-20
Peculiar Immunohistochemical Findings That May Actually be Helpful, Once You Know About Them
Diffuse TGCT Desmin
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EMA
Angiomatoid FH Desmin CD68 ©2016 MFMER | slide-23 ©2016 MFMER | slide-24
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S100 Desmin
Ossifying fibromyxoid tumor S100 NF ©2016 MFMER | slide-25 ©2016 MFMER | slide-26
S100 CD117
EMA SYN ©2016 MFMER | slide-27 ©2016 MFMER | slide-28
#74: Composite HE with NE Marker Expression: An Aggressive Variant
SYN
CD31 ERG SYN CD34 ©2016 MFMER | slide-29 ©2016 MFMER | slide-30
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Other Confusing and Sometimes Wholly Unexpected Immunohistochemical Findings
Sclerosing ALT / WDL
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MDM2 IHC
Lipoma-like ALT / WDL MDM2 CISH Fat necrosis MDM2 IHC ©2016 MFMER | slide-33 ©2016 MFMER | slide-34
CD31 Angiosarcoma CD31 ©2016 MFMER | slide-35 ©2016 MFMER | slide-36
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63F with arm mass Metastatic RCC CD31 and lung nodules ©2016 MFMER | slide-37 ©2016 MFMER | slide-38
Keratin CDX2
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Pulmonary schwannoma S100 protein
Desmin MYOD1 SOX10 TTF1
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Conclusions • Aberrant expression of intermediate filaments and/ or neuroendocrine markers is relatively common amongst soft tissue tumors, in particular Ewing sarcoma, endothelial tumors and rhabdomyosarcoma • For certain mesenchymal tumors, unusual patterns of immunoreactivity may actually serve as valuable clues to the correct diagnosis • Careful morphological observation and application of an appropriate panel of immunohistochemical markers are critical to avoid misdiagnoses based on a single aberrant result
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