SESSION TITLE: Cancer Student/Resident Case Report Posters I
SESSION TYPE: Medical Student/Resident Case Report
PRESENTED ON: Tuesday, October 28, 2014 at 01:30 PM - 02:30 PM
INTRODUCTION: Cancer of unknown primary (CUP) is defined as a histologically confirmed metastatic carcinoma in the absence of a detectable primary cancer. The key characteristics of CUP are early dissemination, short duration of clinical symptoms related to sites of metastases, aggressive clinical course, and a metastatic pattern that differs from that expected of a known primary cancer.
CASE PRESENTATION: A 62-year-old man with a 125 pack-year smoking history presented with one day of sudden onset bilateral lower extremity weakness and inability to ambulate. Preceding this, the patient had been experiencing gradually worsening lower back pain for 3 months. On initial evaluation, proximal muscle weakness and decreased reflexes were noted in bilateral lower extremities without loss of sensation. CT imaging of the spine confirmed suspicion of spinal cord compression, revealing a large, lytic, soft tissue mass involving the right T7 vertebral body with severe canal stenosis. The patient underwent emergent spinal cord decompression with corpectomy. A tan mass measuring 8 x 7.7 x 2.5 cm in aggregate was removed and histology revealed a metastatic mucin-producing adenocarcinoma with immunostains strongly positive for CK-7 (Fig 1) and Napsin A (Fig 2), suggestive of lung primary. TTF-1, Pax 8, CK-20,CDX-2, CA19-9, and PSA staining were negative, excluding adenocarcinoma of esophageal, colon, pancreas, or prostate origin. CT imaging of the chest/abdomen/pelvis was obtained to identify primary tumor, showing a lytic lesion in the left ischium and a small mediastinal lymph node, without any detectable primary lung mass.
DISCUSSION: CUP occurs in 3-5% of all cancer cases and lung cancer presenting as CUP involves the bone in only about 4% of cases. Adenocarcinoma is the most common histopathology of CUP. On immunohistochemical analysis, 85% of lung cancers are positive for CK-7 and Napsin A is a sensitive marker for lung adenocarcinoma with positivity in up to 80% of cases. Lung cancer and CUP represent a significant proportion of spinal cord compression syndrome as initial presentation of malignancy. Optimal treatment strategies for CUP are not clearly defined and choice of therapeutic intervention relies on tissue diagnosis. In our case, combination chemo-radiation therapy was pursued based on the diagnosis of non-small cell lung carcinoma by histopathlogical analysis.
CONCLUSIONS: The differential diagnosis of primary lung carcinoma, particularly in a patient with a significant smoking history, should always be considered in cases of CUP in a patient with spinal cord compression syndrome as initial presentation of malignancy.
Reference #1: Pavlidis, N. Cancer of unknown primary site. Lancet 2012; 379: 1428-35.
Reference #2: Varadhachary, G. et al. Diagnostic Strategies for Unknown Primary Cancer. Cancer 2004; 100(9):1776-85
Reference #3: Schiff, D, et al. Spinal epidural metastasis as the initial manifestation of malignancy: clinical features and diagnostic approach. Neurology. 1997;49(2):452.
DISCLOSURE: The following authors have nothing to disclose: Larysa Gromko, Shanchita Ghosh, Gregory Conti, Sami Harawi, Madhu Parmar
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