序文：いわゆる「ほくろ」と臨床診断された病変には，悪性黒色腫との鑑別がむずかしい中間悪性の病変が含まれる。この割合を調査した。
 方法：当院皮膚科において色素性母斑と臨床診断された病変および，切除後に後天性色素性母斑と病理診断された病変329検体をAckerman分類に従って分類し，臨床診断が色素性母斑であった割合と病理組織学的に中間悪性と診断された割合を調査した。
 結果：対象病変のうち，臨床診断が色素性母斑であった割合は89.0％であった。Spitz nevusに分類された割合が1.8％で最も少なく，さらに臨床診断が色素性母斑であった割合も66.7％で一番低かった。中間悪性または悪性と診断したものが全体の1.8％を占め，Clark nevus，Spitz nevusとの鑑別を要した。
 考察：術前に「ほくろ」と診断されていても，病理組織学的に中間悪性または悪性と診断される病変は決してまれではない。特にSpitz nevusはこれらの病変と鑑別が必要な割合が高く，臨床診断もむずかしいことから注意が必要な「ほくろ」であると考えられた。

 序論：クマによる外傷は増加傾向にある。クマ外傷の特徴や診療の注意点を検討した。
 方法：2016年１月から2020年12月までに当院で経験したクマ外傷について，診療録を基に後ろ向きに性別，年齢，受傷状況，受傷部位，初期治療，受傷後の経過について検討した。
 結果：男性８例，女性２例で，平均年齢は73歳であった。10月の午前中，晴れ，人の生活圏（里山地域），頭頚部や上肢に受傷した例が多かった。顔面に受傷した半数以上で顔面骨骨折を認め，全例で軟部組織損傷を認め，即日再建手術が行われた。全例で予防的抗菌薬が投与され，感染例は認めなかった。
 考察：受傷月や受傷時間，受傷部位は他の報告と同様であったが，受傷場所は他の報告と異なっていた。これは，里地里山の荒廃や食糧不足などでクマが人の生活圏に出現し，人里での受傷が増加したことによると考えられる。今後もクマ外傷は増加する可能性があり，特徴を把握することは治療に有用である。

 Morel-Lavallée Lesion (MLL) is a closed degloving soft tissue injury that occurs after trauma. Although it requires early diagnosis and treatment, no standard treatment has been established. We report a 68-year-old male with MLL, who was treated with continuous suction drainage therapy. He was diagnosed as MLL after conservative treatment for traffic trauma of the right lower extremity. The RENASIS^Ⓡ drain accessory, which is used in negative pressure wound therapy, was used as a suction device. The drain was placed from the thigh to the lower abdomen, and suction was applied at -80 mmHg for 15 days. The disappearance of subcutaneous fluid collection was observed 33 days after the injury and no recurrence was observed 3 months after the injury. This procedure may be a useful method for treating MLL because it is surgically less invasive and easier to perform.

 Metronidazole-induced encephalopathy (MIE) is a relatively rare disorder that causes central nervous system dysfunction including cerebellar ataxia and external ophthalmoplegia. We experienced two cases of MIE during the treatment of refractory leg ulcers. The patients' clinical courses, specific magnetic resonance imaging findings, and significant improvement after cessation of metronidazole led to a definitive diagnosis of MIE. There have been a few reports of irreversible loss of consciousness; however, in both the present cases, the symptoms were reversible and improved within a week. Herein, we review the literature relating to MIE and aim to promote the recognition of MIE in plastic and reconstructive surgery.

 Retronychia is a condition of proximal nail plate in growth into the proximal nail fold that is associated with multiple generations of the nail plate, which causes pain and paronychia. It is not widely known and is rarely diagnosed, resulting in few case reports. Herein, we report six cases of retronychia diagnosed in our department between April and December in 2021. All cases were cured immediately by the removal of the total nail plate. Furthermore, postoperative taping of the toe and application of hydrocolloid on nail beds aided good nail growth. Retronychia is suspected when there is refractory proximal nail fold inflammation that is resistant to antibiotics and antifungals. Nail plate avulsion is an effective treatment.

 We herein report a case of facial malformation with a right macrostomia, bilateral accessory auricular appendages, and a left cleft lip and palate. Macrostomia is a symptom of first and second branchial arch syndrome. A three-day-old Japanese boy was referred to our hospital for the treatment of his cleft lip and palate. He had a left cleft lip and palate as well as right macrostomia and bilateral accessory auricular appendages. A clinical diagnosis of first and second branchial arch syndrome complicated with unilateral cleft lip and palate was made. His macrostomia, cleft lip, and accessory auricular appendages were treated at five months old. The clinical course after surgery was satisfactory. Palatoplasty will be performed in the future.

 Pseudoaneurysms rarely occur in peripheral arteries beyond the lower leg. Herein, we report a case of tibial nerve palsy due to the compression of a pseudoaneurysm of the posterior tibial artery caused by trauma. The patient was a 34-year-old man who suffered a puncture wound from glass in the right Achilles tendon area. There was no pulsatile bleeding, and the glass fragment was removed without any problems; however, the patient experienced pain and difficulty walking on day 12 of the injury. It took time to determine the cause, but a pseudoaneurysm was identified on contrast-enhanced computed tomography. We resected the pseudoaneurysm, thereby resulting in symptomatic improvement. In cases presenting with delayed onset of neurological symptoms following an injury, an aneurysm in the accompanying artery should be considered as a possible cause.