Chemical burns caused by hydrofluoric acid are rare; however, they cause rapid and deep tissue necrosis. In this report, three cases of chemical burns caused by hydrofluoric acid and their treatments are described. Hydrofluoric acid chemical burns are characterized by erythema, white skin maceration, and severe pain. In this study, a lubricating jelly containing calcium gluconate was prepared to treat these chemical burns. We administered a combination treatment consisting of percutaneous administration of the lubricating jelly containing calcium gluconate and local subcutaneous injection. This combination treatment may provide short-term pain relief and be useful in the treatment of chemical burns caused by hydrofluoric acid.

 We encountered two cases of unilateral congenital lacrimal fistula, both of which were treated surgically, and good outcomes were achieved. In one case, MRI was performed under sedation as part of preoperative assessment; however, it proved to be of limited value. Although no definitive treatment policy has been established for congenital lacrimal fistulas, the method of inserting a bougie into both the lacrimal fistula and the inferior lacrimal punctum is considered a useful surgical approach. This method facilitates the identification of the fistula's attachment site, thereby reducing the risk of injury to the lacrimal canaliculus.

 Ectopic hamartomatous thymoma (EHT) is an extremely rare, benign, soft tissue tumor characterized by its occurrence in the cervical to sternoclavicular region mainly in middle-aged and elderly men. The border between the tumor and its surroundings is often clear on imaging; however, the interior of the tumor may be heterogeneously delineated, making it difficult to distinguish it from a malignant tumor. Herein, we present the case of an 80-year-old man with a 30 mm subcutaneous tumor on the right clavicle that was initially suspected to be an epidermoid cyst. We excised the cyst via biopsy. Although clinical and imaging findings were inconclusive, histopathological analysis revealed the tumor to be EHT. At the two-year postoperative follow-up, no recurrence was observed. This case highlights the importance of considering EHT in the differential diagnosis of tumors located in the cervical to sternoclavicular region and differentiating them from malignant tumors.

 Squamous cell carcinoma (SCC) is a known sequela of chronic inflammation. Herein, we present a case of a 72-year-old man who developed SCC following intramuscular (IM) injections that he received in his childhood. The side effects of IM injection, such as induration, redness, and ulceration, are well recognized and the present patient suffered from induration. Repeated drainage of pus from the IM injection site for two decades before biopsy confirmed the diagnosis of SCC. This case suggests that patients who receive IM injections have a potential risk of developing SCC due to the ensuing chronic inflammation. Based on a literature review, we report on the frequency of adverse events after IM injection and their relative risks taking into consideration the different agents used.

 We report a case of major chemical injury caused by a mixture of sulfuric acid and chromic anhydride. A 19-year-old male fell into a tank containing sulfuric acid and chromic anhydride in a chemical plant and sustained a 50% total body surface area chemical burn. Emergency debridement was performed, and the patient was administered a high volume of fluids and ventilator management. Acute renal failure was observed, resulting in multiple organ failure due to acute chromium poisoning. Hemodialysis was initiated; however, the patient died due to deterioration of his condition caused by acute chromium poisoning.
 Chromic anhydride is widely used in the chemical industry for plating and dyes. When absorbed percutaneously through chemical injury, it causes acute chromium poisoning, which rapidly leads to multiple organ damage and is fatal. Rapid debridement is a treatment option for inhibiting percutaneous absorption.