大唾液腺無發育為一少見的先天疾患，可以沒有症狀，也可能以口乾、吞嚥困難、 齲齒等症狀來表現。大唾液腺無發育有時也可能合併其他外胚層先天發育異常。此案 例報告中，我們報告一位以左側頸部腫塊為表現，疑似頷下腺腫瘤，後來切片確診為 瀰漫大B 細胞淋巴瘤之患者，同時意外發現有先天雙側頜下腺無發育之情況。此個案 提醒臨床醫師，在無先天異常、也無口乾症狀之病患中，仍可能出現先天大唾液腺無 發育之情況。

Major salivary gland agenesis, a rare condition, may be asymptomatic or exhibit symptoms, such as dry mouth, dysphagia, and dental caries. Although uncommon, various ectodermal developmental syndromes associated with major salivary gland agenesis have been reported. Here, we report a patient who presented with a left submandibular triangle neck mass mimicking a salivary gland tumor, and received the final diagnosis of diffuse large B-cell lymphoma after excisional biopsy. Moreover, bilateral submandibular gland agenesis was incidentally detected during physical examination and image study. Though submandibular gland is the major structure in the submandibular triangle, its agenesis may occur even in nonsyndromic and nonxerostomic patients.