Primary Merkel cell tumor: a clinical analysis of eight cases

In recent years, an unusual biologic behavior of Merkel cell tumor (MCT) has been noted. In some patients, the tumor was indolent and well controlled by therapy, while in others it was lethal in a few months. Even though the majority of the reported cases are between these two biologic extremes, it seems evident that there is a high variability in the clinical course of the tumor.

A clinical analysis of eight cases of primary Merkel cell tumor was performed. All the patients presented with similar clinical features: age, tumor staging, duration of the disease, lack of complicating cutaneous or systemic diseases. On the basis of these common findings, which made this group quite homogeneous, our attempt was to identify other clinical signs that could correlate with the local recurrence and/or the onset of metastases. The outcome of our patients, in fact, was quite variable.

The tumor size, the clinical aspect at presentation (single, multiple nodules, or plaque), the histologic pattern (all were of the trabecular type), and immunohistology did not correlate with the outcome.

We report the rare occurrence of MCT in the perianal area, which suggests that it should be included in the differential diagnosis of perianal tumors, the very aggressive behavior of the tumor in two patients (death < 6 months from diagnosis), which confirms how the prognosis for MCT is unpredictable even if the diagnosis is established at an incipient stage and the tumor promptly removed.