Merkel cell carcinoma: a rare cause of hypervascular nasal tumor

Abstract

Cutaneous neuroendocrine carcinoma, first described in 1972, is an aggressive disease usually occurring in sun-exposed skin. Other sites have been described, however; such tumors occasionally occur within the nasal fossa. A high rate of metastasis (>30%) explains the poor prognosis. Descriptions of the imaging features of these tumors, mainly located in cutaneous region, are rare. We therefore present the imaging features of two cases of Merkel cell carcinoma involving the sinonasal region, suggestive of a hypervascular tumor.

fig 1.

Case 1. A, Axial, unenhanced CT scan through the inferior turbinate shows a large, homogeneous soft-tissue mass in the right nasal fossa. B, Bone-window image (same level as A) shows aggressive destruction of the nasal septum and intersinonasal wall. C, Coronal T1-weighted imaging with parameters 500/14/4 (TR/TE/excitations) shows the large tumor of intermediate signal intensity with extension into the skull base. Note the retention of mucosal secretion within the right maxillary sinus, of discrete higher signal intensity (arrowhead). D and E, Dynamic T1-weighted imaging with parameters 500/14/4 (TR/TE/excitations) shows early enhancement (D) of the tumor 37 seconds after contrast medium administration (white arrow). Note that the mucosa overlying the inferior turbinate is not yet enhanced. At 75 seconds after contrast medium administration (E), the tumor is more enhanced. Notice the linear enhancement of the dura mater (arrowhead). F, Immunostaining for keratin. Positivity has a distinct perinuclear dot-like quality, a characteristic feature of Merkel-cell carcinoma.

fig 2.

Case 2. A, Axial unenhanced CT scan image shows a large homogeneous mass without calcifications destroying the lamina papiracea and the nasal septum. B, Coronal T2-weighted imaging with parameters 4000/91/3 (TR/TE/excitations) shows stretching of the right optical nerve by the tumor, which shows intermediate signal intensity with cystic areas. C and D, Six months after chemo- and radiotherapy, T1-weighted images before and after contrast material administration (parameters 480/12/2 [TR/TE/excitations]) show large necrotic intratumoral areas.