Somatostatin analogue scintigraphy in Merkel cell tumours.

Background: Merkel cell tumours are rare neoplasms of the skin with frequent regional and distant metastases. Scintigraphy with the radiolabelled somatostatin analogue octreotide is a possible method for in vivo localization of the primary tumour and its metastases.
Objectives: To estimate the diagnostic value of indium (111) -octreotide scintigraphy (Octreoscan in detecting metastases.
Methods: Scans of 11 patients with Merkel cell carcinoma were evaluated, in whom scintigraphy was performed in addition to the conventional investigations, chest X-ray, ultrasonography and computed tomography (CT).
Results: In four cases metastases were found both by scintigraphy and by conventional methods; two investigations showed a suspicious accumulation of radioactivity on scintigraphy that could not be confirmed by CT and clinical progression. In three cases CT-verified metastases were not found by scintigraphy. Two patients were found to be tumour free, i.e. free of metastases by scintigraphy and conventional methods, indicating true-negative results.
Conclusion: These data confirm that scintigraphy with the radiolabelled somatostatin analogue octreotide is not clinically helpful in detecting metastases from Merkel cell carcinoma. In this relatively small sample the method generated false-positive or false-negative results in five of 11 cases.