Extrapulmonary Small Cell Carcinoma Workup

Updated: Apr 16, 2015
  • Author: Irfan Maghfoor, MD; Chief Editor: Jules E Harris, MD, FACP, FRCPC  more...
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Workup

Laboratory Studies

No laboratory investigations aid in the diagnosis of extrapulmonary small cell carcinoma. Most of the laboratory studies done in the workup are to assess end organ function prior to instituting therapy, especially chemotherapy, or to diagnose a suspected paraneoplastic syndrome.

Complete blood count with differential is obtained to assess bone marrow reserve, but it may give clues to bone marrow infiltration by the tumor. Bone marrow infiltration is suspected based on a leukoerythroblastic (presence of red and white blood cell precursors in peripheral blood) picture of peripheral blood.

Blood urea nitrogen and serum creatinine and electrolytes are obtained to asses renal function prior to instituting potentially nephrotoxic drugs as well as estimate renal clearance of chemotherapeutic agents. In addition, low sodium and abnormalities in other electrolytes such as potassium may point towards presence of a paraneoplastic syndrome.

Serum bilirubin and transaminases are obtained to assess liver function and for appropriate dosing of hepatically cleared chemotherapeutic agents.

Serum calcium is assessed for suspected hypercalcemia and bone metastases.

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Imaging Studies

The diagnosis of extrapulmonary small cell carcinoma by definition requires a chest radiograph, computed tomographic scan, or both without findings of chest involvement.

  • Chest radiograph is obtained to exclude pulmonary involvement.
  • CT scan of chest, abdomen, and pelvis is obtained to exclude pulmonary involvement and stage the extent of disease.
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Procedures

Bone marrow aspiration and biopsy are performed to confirm or rule out bone marrow involvement in case of peripheral blood abnormalities. Some authors recommend that bone marrow biopsy should be done in every patient to confirm limited disease.

Sputum cytology, bronchoscopy, or both are performed to exclude pulmonary origin of small cell carcinoma.

Special tests that may be performed, depending on primary site of origin, include the following:

  • Upper endoscopy: Esophagus
  • Direct laryngoscopy, bronchoscopy, and upper endoscopy: Origin in head and neck region
  • Cystoscopy: Urinary bladder
  • Lower endoscopy: Rectum and large bowel
  • Pelvic examination: Cervix and uterus
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Histologic Findings

Extrapulmonary small cell carcinoma histologically consists of sheets of uniform small round cells with scant cytoplasm, dense nuclei, and indistinct nucleoli.

Immunohistochemical stains with silver impregnated stains usually have positive results.

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Staging

There is no American Joint Committee on Cancer (AJCC) staging classification for extrapulmonary small cell carcinoma. In the reported literature, extrapulmonary small cell carcinoma is universally staged similarly to small cell carcinoma of lung, that is limited stage and extensive stage.

  • Limited stage: Tumor is confined to organ of origin with or without regional lymph node involvement. Alternatively, limited stage has also been defined as that encompassed within one radiation port.
  • Extensive stage: Disease has spread to distant organs or beyond regional lymph nodes.
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