序論：ピコ秒レーザーenLIGHTen^®の短所を補う，老人性色素斑治療の新しい手法を報告する。
 方法：波長532nm，パルス幅750ps，スポットサイズ２～３mmの設定で，病変全体に明瞭なimmediate whitening phenomenonが観察されるまで密に照射する。
 結果：27歳，男性。左頬部の老人性色素斑に対しenLIGHTen^® SRを使用し，波長532nm，スポットサイズ２mm，フルエンス1.0J/cm²，５Hzで治療を行った。１ヵ月後に炎症後紅斑や色素沈着，明らかな残存病変は認められなかった。
 考察：小口径で密に照射することで，病変の残存リスクと周囲組織への熱損傷による炎症後色素沈着のリスクを下げる可能性がある。
 結論：本手法は機器の特性を補い，習熟度に依存しにくい実施しやすい方法と考えられる。

 A congenital external lacrimal sac fistula opens from the lacrimal sac or duct into the skin near the inner corner of the lower eyelid. It is considered a relatively rare condition. We encountered a case where the fistula recurred following a resection-only fistulectomy. The fistula was subsequently removed by ligating the stump in our department. The patient has remained recurrence-free.
 Complete removal of the fistula duct is generally required to treat this condition; however, the necessity of ligating the stump remains to be elucidated. In this study, we compared the recurrence rates of this condition using studies reported in Japan and overseas. We found no significant difference in recurrence rates between ligation and resection alone.

 Alveolar soft part sarcoma (ASPS) is a rare malignant soft tissue tumor that predominantly affects young adult women. ASPS constitutes less than 1% of all malignant soft tissue tumors. ASPS typically presents as a gradually enlarging mass in the extremities, head, and neck. However, it can also occur in other parts of the body. Herein, we report a case of ASPS occurring in the pectoralis major muscle of a 69-year-old man. He was referred to our institute with a soft tissue mass in the left thoracic region. CT, MRI, and fine-needle biopsy raised the suspicion of a soft tissue malignancy in the pectoralis major muscle. FDG-PET/CT confirmed the absence of additional lesions beyond the left thoracic region. The patient underwent radical resection of the tumor. Histopathological examination of the resected tumor confirmed the diagnosis of ASPS. Follow-up one year after surgery revealed no signs of local recurrence or distant metastasis. This case is particularly noteworthy as ASPS in the pectoralis major muscle is a rare occurrence. A literature search identified the present case as only the second reported case, and the first in Japan.

 Bilateral orbital floor blowout fractures are rare. Most cases are classified as impure-type fractures, which are characterized by a fracture that extends to the surrounding orbital margin. Bilateral orbital floor blowout fractures of the pure type are extremely rare. Most reported cases of pure-type fractures are associated with assault. In this report, we present two cases of bilateral orbital floor blowout fractures resulting from a single traumatic event. Both cases involved fractures in the bilateral infraorbital walls and nasal bones, without any fractures in the periorbital area; thus, they were classified as pure-type fractures. Notably, we found no evidence of damage to the face guard of the helmet, glasses, or eyes, which suggests that the mechanism of the fracture was due to a buckling force rather than a hydraulic force.

 Lacrimal sac diverticulum is a relatively rare condition characterized by the formation of a continuous cystic structure originating from the lacrimal sac. While it is often asymptomatic, symptoms, such as epiphora, swelling near the medial canthus, and drainage of pus, may occur. Diagnosis is often challenging because there is no specific test. Treatment generally involves the use of antibiotics. Lacrimal sac diverticulum should be considered a differential diagnosis when evaluating a mass in the medial canthus. Herein, we present a case of lacrimal sac diverticulum with repeated episodes of swelling in the medial canthus as the primary complaint.