眼瞼腫脹を契機に神経線維腫症1型と診断された1例

A case of neurofibromatosis type 1 diagnosed by eyelid swelling

要約　目的：神経線維腫症1型（neurofibromatosis type 1：NF1）は，カフェオレ斑や神経線維腫を主徴とする常染色体顕性の遺伝性疾患である。小児期に特徴的皮膚所見から診断されることが多い。今回筆者らは，30代で眼瞼腫脹を契機にNF1と診断された1例を経験したので報告する。

症例：31歳，男性。数年前からの右上眼瞼の腫れを主訴に前医を受診し，専門施設での精査を勧められ，当科へ紹介となった。初診時の矯正視力は右（0.9），左（1.2）であった。右上眼瞼の腫脹と，これによる瞳孔領にかかる眼瞼下垂が観察されたが，硬結は触知されなかった。悪性リンパ腫や自己免疫疾患などの可能性を考え血液検査や眼窩部単純CTを施行したが，CTで右上眼瞼の肥厚を認めるのみで，ほかに有意な結果は得られなかった。再診時に前眼部を子細に観察したところ，両眼にLisch結節を認めたため，頸部，両前腕部を観察したところ，カフェオレ斑を認めた。NF1を疑い皮膚科へ紹介し，四肢体幹に多数のカフェオレ斑や神経線維腫が認められ，NF1と診断された。続いて，右上眼瞼腫脹の原因がNF1による神経線維腫であると考えられたため形成外科に紹介し，生検目的および整容面と視野の改善目的に眼瞼の減量術が行われた。切除検体の病理組織学的所見は，神経線維腫として矛盾しない結果であった。

結論：NF1は小児期に診断がついていることが多く，眼瞼腫脹を契機に診断に結びつくことは稀であるが，鑑別すべき疾患の1つとして考える必要がある。

Abstract　Purpose：Neurofibromatosis type 1（NF1） is an autosomal dominant genetic disorder characterized by café-au-lait spots and neurofibromas. Most cases are diagnosed during childhood based on characteristic skin findings. Here, we report the case of a patient diagnosed with NF1 due to eyelid swelling in his 30s.

Case：A 31-year-old man who had been aware of swelling in his right upper eyelid for several years visited a doctor and was referred to our department for a thorough examination. The corrected visual acuity was（0.9） in the right eye and（1.2） in the left eye. Swelling of the right upper eyelid caused ptosis of the pupillary zone；however, no induration was palpated. Blood tests and simple computed tomography（CT） scan of the orbit were performed to rule out malignant lymphoma and autoimmune disease；however, no significant results were obtained other than the thickened right upper eyelid observed on CT. A detailed examination of the anterior eye revealed Lisch nodules in both eyes upon the return of the patient to the hospital. Further examination of the neck and forearms revealed the presence of café-au-lait spots. NF1 was suspected, and the patient was referred to a dermatologist. Thereafter, numerous café-au-lait spots and neurofibromas were observed on the limbs and trunk. Consequently, the patient was diagnosed with NF1 and referred to the Department of Plastic Surgery because an NF1 induced-neurofibroma of the eyelid was suspected. Eyelid debulking surgery was then performed for biopsy, as well as cosmetic and visual improvement. Histopathological findings of the resected specimens were consistent with those of a neurofibroma.

Conclusion：NF1 is typically diagnosed during childhood in most cases. Although it is rare to diagnose NF1 based on eyelid swelling, this case should be considered as a possible differential diagnosis.