ABC Medical Notes.com

About

• Uncommon diagnosis of malignant cells without knowledge of the primary source
• Some times the primary is never found

Aetiology

• The primary cancer is very small and grows slowly.
• The bodys immune system killed the primary cancer.
• The primary cancer was removed during surgery for another condition

Cytology

• Squamous cell carcinoma (5%)
• Undifferentiated carcinoma, neuroendocrine tumour/carcinoma, undifferentiated neoplasm (30% all included)
• Adenocarcinoma, poorly differentiated carcinoma (65%),

Clinical

• Metastases in chest, adrenals, bone, brain
• Ask about bowel and upper GI symptoms
• Look for melanoma on skin

Pathology

• Excisional biopsy: The removal of an entire lump of tissue.
• Incisional biopsy: The removal of part of a lump or a sample of tissue.
• Core biopsy: The removal of tissue using a wide needle.
• Fine-needle aspiration: The removal of tissue or fluid using a thin needle.

Investigations: Hunting the primary

• FBC, LFTs, U&E, TFT, PSA other-directed serum tumour markers
• CT scan: Often a contrast CT of the chest abdomen and pelvis is performed
• Bone scan if symptomatic
• MRI (magnetic resonance imaging): of chest and abdomen and pelvis may be considered
• PET scan (positron emission tomography scan): A procedure to find malignant tumour cells in the body. A small amount of radioactive glucose is injected into a vein. The PET scanner rotates around the body and makes a picture of where glucose is being used in the body. Malignant tumour cells show up brighter in the picture because they are more active and take up more glucose than normal cells do.
• Mammogram : An x-ray of the breast.
• Endoscopy: A procedure to look at organs and tissues inside the body to check for abnormal areas. An endoscope is inserted through an incision (cut) in the skin or opening in the body, such as the mouth. An endoscope is a thin, tube-like instrument with light and a lens for viewing. It may also have a tool to remove tissue or lymph node samples, which are checked under a microscope for signs of disease. For example, a colonoscopy may be done.
• Tumour marker test: A procedure in which a sample of blood, urine, or tissue is checked to measure the amounts of certain substances made by organs, tissues, or tumour cells in the body. Certain substances are linked to specific types of cancer when found in increased levels in the body. These are called tumour markers. The blood may be checked for the levels of CA-125, CgA, alpha-fetoprotein (AFP), beta-human chorionic gonadotropin (Beta-hCG), or prostate-specific antigen (PSA)
• Fine needle aspiration (FNA) or core biopsy (preferred) of most accessible lesion3 if not already performed, or if insufficient tissue is available for diagnosis and/or predictive/prognostic markers and/or molecular analysis

Commonly utilized immunoperoxidase stains to assist in the differential diagnosis of poorly diferentiated neoplasms

• Breast Cancer Estrogen receptor (ER), gross cystic disease fluid fibrous protein-15 (GCDFP-15), mammaglobin, HER-2 neu, GATA-3
• Lung Cancer Thyroid transcription factor (TTF-1), surfactant protein A, napsin A
• Prostate Cancer PSA, prostatic acid phosphatase (PAP), alpha-methylacyl CoA racemase/P504S (AMACR/P504S) protein
• Lymphoma Leukocyte common antigen (LCA), CD3, CD4, CD5, CD10, CD20, CD45, PAX5, Bcl-2, Bcl-6, cyclin D1
• Mullerian/Ovarian Estrogen receptor (ER), WT-1, PAX8
• Sarcoma Desmin1, factor VIII2, CD31, smooth muscle actin for leiomyosarcoma, MyoD1, myogenin for rhabdomyosarcoma
• Neuroendocrine Tumor Chromogranin, synaptophysin, CD56
• Germ Cell Tumor ßHCG, aFP, OCT3/4, CKIT, SALL4, CD30 (embryonal)
• Urothelial Malignancies CK7, CK20, thrombomodulin, GATA-3
• Colorectal Cancer CK7, CK20, CDX-2, carcinoembryonic antigen (CEA), SATB2
• Renal Renal cell carcinoma (RCC), CD10, PAX8
• Hepatocellular Carcinoma HepPar-1, CD10, glypican-3, arginase-1
• Melanoma S100, HMB-45, tyrosinase and melan-A, SOX10 Thyroid Thyroglobulin, thyroid transcription factor (TTF-1), PAX8

Management

• Specialist oncology referral and use of the cancer MDT process
• Palliative chemo for some

References

• Cancer Of Unknown Primary Algorithm