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Table 75-1

Possible Pathologic Evaluation of Biopsy Specimens from Patients with Metastatic Cancer of Unknown Primary Site

Evaluation/FindingsSuggested Primary Site or Neoplasm
Histology (hematoxylin and eosin staining)
Psammoma bodies, papillary configurationOvary, thyroid
Signet ring cellsStomach
Immunohistology
Leukocyte common antigen (LCA, CD45)Lymphoid neoplasm
Leu-M1Hodgkin's disease
Epithelial membrane antigenCarcinoma
CytokeratinCarcinoma
CEACarcinoma
HMB45Melanoma
DesminSarcoma
ThyroglobulinThyroid carcinoma
CalcitoninMedullary carcinoma of the thyroid
MyoglobinRhabdomyosarcoma
PSA/prostatic acid phosphataseProstate
AFPLiver, stomach, germ cell
Placental alkaline phosphataseGerm cell
β-human chorionic gonadotropinGerm cell
B, T cell markersLymphoid neoplasm
S-100 proteinNeuroendocrine tumor, melanoma
Gross cystic fluid proteinBreast, sweat gland
Estrogen and progesterone receptorsBreast
Factor VIIIKaposi's sarcoma, angiosarcoma
Thyroid transcription factor 1 (TTF-1)Lung adenocarcinoma, thyroid
Calretinin, mesothelinMesothelioma
URO-III, thrombomodulinBladder
Flow Cytometry
B, T cell markersLymphoid neoplasm
Ultrastructure
Actin-myosin filamentsRhabdomyosarcoma
Secretory granulesNeuroendocrine tumors
DesmosomesCarcinoma
PremelanosomesMelanoma
Cytogenetics
Isochromosome 12p; 12q(-)Germ cell
t(11;22)Ewing's sarcoma, primitive neuroectodermal tumor
t(8;14)aLymphoid neoplasm
3p(-)Small cell lung carcinoma; renal cell carcinoma, mesothelioma
t(X;18)Synovial sarcoma
t(12;16)Myxoid liposarcoma
t(12;22)Clear cell sarcoma (melanoma of soft parts)
t(2;13)Alveolar rhabdomyosarcoma
1p(-)Neuroblastoma
Receptor Analysis
Estrogen/progesterone receptorBreast
Molecular Biologic Studies
Immunoglobulin, bcl-2, T cell receptor gene rearrangementLymphoid neoplasm

aOr any other rearrangement involving an antigen-receptor gene.

Abbreviations: AFP, α-fetoprotein; CEA, carcinoembryonic antigen; PSA, prostate-specific antigen.