Low-grade fibromyxoid sarcoma (LGFMS) is a rare soft tissue tumor that has a tendency to grow in the deep soft tissue of the trunk and extremities. Despite its benign appearance, the tumor has a high recurrence rate and metastatic potential. LGFMS in the perineal space is rare, and only a few cases have been reported. We present the first case of LGFMS to be located at the external anal sphincter. A 27-year-old male patient admitted to our Surgical Department with perianal pain and swollen for a year. The digital rectal examination revealed a perianal mass. Oral metronidazole and analgesia were prescribed on suspicion of perianal abscess failed to alleviate the symptom; hence, the patient was scheduled for surgery. Intraoperative diagnosis revealed an encapsulated tumor in the external anal sphincter that extended from the perianal region orally to the pararectal space. The results of immunohistochemistry (MUC4 staining) and FUS gene rearrangement by fluorescence in situ hybridization confirmed the diagnosis of LGFMS. This case is unique in terms of the location of the rare soft tissue tumor. Although LGFMS is considered low grade, its unpredictable behavior necessitates a long-term follow-up.

Concurrent mutations of synchronous multiple primary non-small cell lung cancer (SMPNSCLC) is rare, and only a few cases have been reported. Herein, we present a case of early-stage SMPNSCLC with T790M and L858R mutations. A 68-year-old male patient presented to the Thoracic Surgery Department due to a tumor in the right lower lung. The tumor was detected more than 5 years previously during a health examination; however, the patient ignored the problem because the clinician at that time stated that the lesion was highly likely to be benign. Chest computed topography (CT) was ordered and the images showed a well-defined tumor in the right lower lung and a faint nodular lesion over the left lower lung field. A CT-guided biopsy results showed the presence of atypical cells and positive staining of TTF-1 and CK7. Surgical intervention was performed. The right- and left-sided tumors disclosed micropapillary predominant adenocarcinoma and acinar-predominant adenocarcinoma, respectively. Both tumors were positive for TTF-1 but negative for ALK and p40. Real-time PCR analysis showed that the right-sided tumor had an epidermal growth factor receptor (EGFR) mutation presenting as point mutation T790M in exon 20, while the left-sided tumor had a point mutation L858R in exon 21 of EGFR. Our patient’s case suggests that tumors resembling a benign pattern with central calcification may be misdiagnosed. Thus, early screening for lung cancer is important, and intensive efforts to make a diagnosis through surgical resection or biopsies to allow for tailored optimal treatment may be preferential for the best patient outcomes.