Ectopic Hamartomatous Thymoma-Case Report

異構性胸腺瘤－病例報告

張家齊(Chia-Chi Chang) ； 黃博琪(Po-Chi Huang) ； 黃大宜(Ta-Yi Huang) ； 李仁傑(Jen-Chieh Lee) ； 黃弘孟(Hung-Meng Huang)

《台灣耳鼻喉頭頸外科雜誌》 54卷4期 (2019/12) Pp. 216-221

https://doi.org/10.6286/jtohns.201912_54(4).216

摘要

Ectopic hamartomatous thymoma (EHT) is an extremely rare benign tumor, mostly involves middle-aged male patients. EHTs are difficult to be differentiated from benign lipomatous neoplasm to some sarcomas. A 47-year-old man came to us because of a painless tumor in his right anterior neck and upper chest for over 10 years. Computed tomography showed a large well-defined mass involving right sternocleidomastoid muscle measuring 11.6 × 9.0 × 7.8 cm, suspecting well-differentiated liposarcoma, or lipoma. Fine needle biopsy was done, but not conclusive. Total excision was performed. The histological findings revealed a well-encapsulated tumor mixed with abundant spindle cells, adipocytes and less proportion of epithelial components, accompanied with rare mitosis and no tumor necrosis. Immunohistochemical analysis showed the spindle and epithelial tumor cells to be positive for cytokeratin-AE1/3, P63 and very low proliferative index (only 1% tumor cells positive staining for Ki67); spindle tumor cells to be immunoreactive to smooth muscle actin and CD34, but negative to desmin, S100, MDM2, confirming the diagnosis of ectopic hamartomatous thymoma. Tumor with initial presentation with a huge single soft tissue tumor at the neck or upper chest wall and the unusual pathological features may easily be misdiagnosed as sarcomatous lesion. It is important to recognize this diagnosis because it follows a benign clinical course and can be cured only by conservative surgical excision.

關鍵字

neck tumor ； ectopic hamartomatous thymoma ； immunohistochemistry ； benign

並列摘要

異構性胸腺瘤是很罕見的良性腫瘤，多好發在中年男性，常難以和一些良性脂肪瘤以及肉瘤做鑑別診斷。1名47歲男性因右頸前一10年的腫瘤來醫院就診，電腦斷層掃瞄顯示此為一顆巨大的腫瘤且範圍含括深至右上胸鎖乳突肌以上，向外拓展至右上胸皮下，大小約11.6 × 9.0 × 7.8 cm，質地上呈現以脂肪組織為主，且有和一些軟組織的混合，診斷上懷疑是脂肪肉瘤或脂肪瘤，超音波穿刺切片無法完全確診且有肉瘤的可能，後切除做病理染色分析。病理結果顯示內含豐富的梭狀細胞，脂肪細胞以及少量的上皮組成且伴隨稀少的細胞分裂，無發現細胞壞死現象。鑑別診斷包含：梭狀細胞脂肪瘤，分化良好的脂肪肉瘤，皮膚纖維肉瘤，纖維肉瘤，脂肪性血管外皮細胞瘤及滑膜肉瘤。免疫染色分析顯示梭狀細胞和上皮細胞瘤對cytokeratin-AE1/3, P63染色為陽性，且增值指數很低，另梭狀細胞又對smooth muscle actin and CD34染色為陽性，但對於desmin, S100, MDM2等染色為陰性，故鑑別此腫瘤為異構性胸腺瘤。此特殊病理組成的腫瘤如果只有少量的樣本，難以和肉瘤鑑別，鑑別此二者對於後續臨床處置分歧極為重要，若為良性腫瘤只需將病竈切除追蹤。

並列關鍵字

neck tumor ； ectopic hamartomatous thymoma ； immunohistochemistry ； benign（頸部腫瘤 ； 異構性胸線瘤 ； 免疫組織化學染色法 ； 良性）