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Pathology ` PATHOLOGY—neOPLASIA Pathology ` PATHOLOGY—neOPLASIA SECtIoN II 227

Important Determine primary site of origin for metastatic tumors and characterize tumors that are difficult to
immunohistochemical classify. Can have prognostic and predictive value.
stains
STAIn TArGeT TuMOrS IDenTIfIeD
Chromogranin and Neuroendocrine cells Small cell carcinoma of the lung, carcinoid
synaptophysin tumor
Cytokeratin Epithelial cells Epithelial tumors (eg, squamous cell carcinoma)
DesMin Muscle Muscle tumors (eg, rhabdomyosarcoma)

GFAP NeuroGlia (eg, astrocytes, Schwann cells, Astrocytoma, Glioblastoma
oligodendrocytes)
Neurofilament Neurons Neuronal tumors (eg, neuroblastoma)
PSA Prostatic epithelium Prostate cancer
S-100 Neural crest cells Melanoma, schwannoma, Langerhans cell
histiocytosis
TRAP Tartrate-resistant acid phosphatase Hairy cell leukemia
Vimentin Mesenchymal tissue (eg, fibroblasts, endothelial Mesenchymal tumors (eg, sarcoma), but also
cells, macrophages) many other tumors (eg, endometrial carcinoma,
renal cell carcinoma, meningioma)

P-glycoprotein Also known as multidrug resistance protein 1 (MDR1). Classically seen in adrenocortical
carcinoma but also expressed by other cancer cells (eg, colon, liver). Used to pump out toxins,
including chemotherapeutic agents (one mechanism of  responsiveness or resistance to
chemotherapy over time).

Psammoma bodies Laminated, concentric spherules with dystrophic calcification A , PSaMMOMa bodies are seen in:
A ƒ Papillary carcinoma of thyroid
ƒ Somatostatinoma
ƒ Meningioma
ƒ Malignant Mesothelioma
ƒ Ovarian serous papillary cystadenocarcinoma
ƒ Prolactinoma (Milk)

Cachexia Weight loss, muscle atrophy, and fatigue that occur in chronic disease (eg, cancer, AIDS, heart
failure, COPD). Mediated by TNF-α, IFN-γ, IL-1, and IL-6.

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