We read with interest the report by Rubio et al1 on "Carcinoid Tumor Metastatic to the Breast" in the October 1998 ARCHIVES. We agree that the presentation is consistent with carcinoid tumor metastatic to the breast; however, consideration should be given to the addition of serum chromogranin A, the somatostatin receptor for scintigraphy, and endoscopic ultrasonography to elucidate the occult primary carcinoid tumor. Chromogranin A is a valuable serum marker for neuroendocrine tumors, with the highest values found in patients with metastatic carcinoids of unknown primary sites. A correlation has been demonstrated between serum chromogranin A levels and somatostatin receptor positivity for midgut carcinoids.2 Evaluation for occult foregut carcinoid tumor should include endoscopic ultrasonography, which has a sensitivity of approximately 90% for tumors smaller than 2 cm.3 Scintigraphy combines the advantage of whole-body imaging with sensitivity of 75% to 100% and specificity of 90% to 100% to detect the unknown primary tumor and other sites of metastasis.4 Following external scintigraphy, gamma-detection probes can be employed intraoperatively to assist in the detection of nonpalpable (<5 mm), surgically occult lesions. 5
Volpe C, Doerr RJ. Somatostatin Receptor Scintigraphy and Endoscopic Ultrasonography for Occult Carcinoid Tumor. Arch Surg. 1999;134(5):575–576. doi:
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