We present a case of a 17-year-old adolescent with a giant pseudocyst of the scalp. The patient presented with a painless, subcutaneous mass located on the top of his head. The mass was elastic, measured 30×30 mm, and was characterized by hair loss. Fluid drained from the punctured mass was subjected to bacterial culture, yielding a negative result. A portion of the mass was incised, and pathological evaluation was performed, which confirmed the diagnosis of a pseudocyst without epithelial lining. We treated the patient with a triamcinolone acetonide injection. Hair growth was observed one month later, and the mass resolved within three months. We recommend puncture and triamcinolone acetonide injection as treatment for pseudocyst of the scalp, with surgical intervention considered if the initial treatment proves ineffective.

 Filler injection is a widely performed minimally invasive procedure for facial rejuvenation. We treated nasal alar necrosis caused by filler injection using a nasolabial flap and a composite graft from the ear. Thirteen years later, a secondary composite graft using the ascending helical crus was performed to treat nostril rim lowering. Reconstruction of the nasal alar due to filler injection in cases with unstable circulation necessitates careful selection of the timing and method of intervention. Long-term postoperative observation is crucial.

 Canaliculops (or canaliculocele), a noninflammatory and noninfectious dilation of the canaliculus, is an extremely rare cause of a medial canthal mass. To date, only 17 cases have been reported worldwide. We report a case of a 59-year-old man with a right medial canthal mass and right lower eyelid ectropion. Clinical examination, contrast-enhanced computed tomography of the lacrimal ducts, and lacrimal duct endoscopy confirmed the diagnosis of canaliculops. The mass was excised following dacryoendoscopy-guided intubation. Histopathological analysis of the resected specimen revealed features that were slightly different from previous reports.

 Lymphoproliferative disorders that develop following the intake of immunosuppressive drugs for autoimmune and inflammatory diseases are termed other iatrogenic immunodeficiency-associated lymphoproliferative disorders (OIIA-LPD). Methotrexate-associated lymphoproliferative disorder (MTX-LPD) is a representative disorder of OIIA-LPD that is associated with the drug methotrexate (MTX) and is difficult to diagnose. Herein, we report a case of a cheek skin lesion in a patient with MTX-LPD, where a biopsy sample was obtained 3-4 mm away from the lesion margin. The quantity of Epstein-Barr virus DNA in the sample was measured, and this method was found to be useful for disease evaluation.

 An 88-year-old man presented with bilateral chest pain one week prior to his visit to our hospital. He had a subcutaneous mass in the anterior thoracic region, which had gradually increased in size and become painful. Incision and drainage of the subcutaneous abscess were performed under local anesthesia; however, there was no improvement. A mediastinal abscess was diagnosed by chest computed tomography. Due to the uncontrolled infection, the surgical field was expanded by resecting the second rib cartilage, and percutaneous and thoracoscopic drainage were reperformed. The soft tissue defect in the anterior chest was reconstructed using a pectoralis major flap.
 Mediastinal abscesses can extend subcutaneously into the anterior thoracic region, leading to the formation of subcutaneous abscesses as the infection progresses. Anterior thoracic subcutaneous abscesses accompanied by severe respiratory symptoms should be treated cautiously due to the potential subcutaneous invasion of mediastinal abscesses.