頭蓋骨転移で発症した悪性paragangliomaの1例

A Case of Malignant Paraganglioma Presenting with Skull Metastases

Ⅰ．はじめに

　Paragangliomaは，副腎髄質以外のクロム親和性細胞から発生する褐色細胞腫である．本来は良性腫瘍であるが，経過中に非クロマフィン組織へ転移し，悪性paragangliomaと診断されることがある．この場合，組織学的には悪性診断は困難である⁵⁾．また，骨へも転移するが，脊椎や体幹骨が多く，頭蓋骨や頭蓋内への転移は稀である^2,8,11,12)．

　今回，中頭蓋窩に骨融解を伴って生じた腫瘍が，7年前に腎門部に原発したparagangliomaからの転移であることが判明した1例を経験したので，文献的考察を加えて報告する．

　A non-functioning paraganglioma is usually benign, however, it may cause distant metastases. There is no histological appearance for the diagnosis of malignancy or absolute criteria for predicting malignant potential. Bony metastases from paraganglioma are known to occur, but, skull metastases are very rare.

　We report a case of intracranial metastases from a renal paraganglioma. A 61-year-old male presented with temporal headache and exophthalmos on the left side. Seven years prior, he underwent surgery to remove a mass in the right renal hilum, which was diagnosed as renal cell carcinoma at that time. Computed tomography and magnetic resonance imaging showed a ring-like enhanced mass in the left middle fossa, which destroyed the sphenoid bone and the lateral wall of the orbit. Another osteolytic lesion was revealed in the occipital bone. The fragile tumor was totally resected. Histopathological study revealed the Zellballen pattern with extensive coagulation necrosis. No apparent nuclear atypia or mitosis were present. Immunohistochemistry showed reactivity for synaptophysin and chromogranin A in the tumor cells. Review of the surgical specimen of the previously resected renal tumor revealed the same pathological and immunohistochemical findings as those of chief cells in the middle fossa tumor. Thus, this tumor was diagnosed as a malignant paraganglioma metastasized from renal paraganglioma. After six cycle chemotherapy with cyclophosphamide and vincristine, his condition was stable for two years, however, he died four years after the diagnosis of malignancy.