Objective: To investigate clinicopathologic features and prognosis of adenoid cystic carcinoma (ACC) involving external auditory meatus. Methods: The clinical presentation and follow-up data of 63 patients with ACC of external auditory canal were collected from January 2006 to February 2017 at PLA General Hospital and Hainan Branch of PLA General Hospital. The clinicopathologic features and prognostic factors of external auditory canal ACC were analyzed. Results: (1) There were 28 males and 35 females and the average age of the first diagnosis was 48.9 years (22-81 years). The tumors showed cribriform pattern in 35 cases (15 cases of late stage), tubular pattern in 14 cases (8 cases of late stage), and solid pattern in 14 cases (9 cases of late stage). Cases with solid pattern was relatively more frequent than that of cribriform pattern and tubular pattern, but the difference was not statistically significant (P>0.05). (2) The average follow-up time was 62.4 months (2-228 months) in the 57 available cases. Among the 33 cases with recurrence, 18 cases had local recurrence and 15 cases had distant metastasis. The mean recurrence time was 40.6 months (2-204 months). Nine patients died of ACC: 2 cases in early stage (died at 48 and 102 months after the first treatment), 7 cases in late stage and 57 with (died at 9, 30, 32, 60, 72, 94 and 228 months). (3) Among the 37 patients with perineural invasion, there were 21 cases of cribriform pattern, 4 cases of tubular pattern and 12 cases of solid pattern; the number of cases in early stage and late stage were 15 and 22, respectively; and the differences were statistically significant (P<0.05). In addition, 31 cases had otalgia among the 37 patients with perineural invasion, where differences were not significant (P>0.05). (4) Thirty of 45 cases with tumor resection or partial resection of temporal bone had recurrence, whereas 3 of 12 cases of tumor combined with superficial lobectomy of parotid gland had recurrence. The difference was statistically significant (P<0.05). Postoperative adjuvant radiotherapy was given in 19 cases, including 7 cases of early stage (2 cases of recurrence), and 12 cases of late stage (8 cases of recurrence), among which there was no significant difference (P>0.05). Conclusions ACC occurring in external auditory canal frequently recurs. Superficial parotid lobectomy at the first operation is necessary to prevent tumor recurrence. Postoperative adjuvant radiotherapy has certain curative effect on patients with early stage tumor, but it does not affect the recurrence rate. Patients at late stage are more prone to perineural invasion than those in early stage. In addition, cribriform and solid patterns are more common that tubular pattern, and there is no significant correlation between perineural invasion and otalgia.

Objective:To explore the clinicopathological and molecular genetic features of adult hepatic mesenchymal hamartoma (MHL).Methods:A total of five confirmed adult MHL cases diagnosed at the Pathology Department of the First Medical Center of the People's Liberation Army General Hospital between 2009 and 2022 were collected. Histomorphological observation and immunohistochemical staining were conducted. Gene detection was performed by next-generation sequencing.Results:Among the five cases, four were male and one was female, aged 46-67 years, with an average age of 56.2 years. The maximum diameter was 5.3-13.5cm, and the average diameter was 9.2cm. Tumors were generally cystic, solid, or mixed cystic-solid. Histopathologically, in four out of five cases of MHL, malignant transformation occurred, of which three cases were malignantly transformed into undifferentiated embryonal sarcoma and one case was malignantly transformed into a malignant solitary fibrous tumor. NAB2-STAT6 gene rearrangements were identified.Conclusion:Adult MHL is a rare kind of tumor with malignant potential, and it is difficult to diagnose with preoperative imaging examinations. A fine-needle biopsy is rarely used for diagnosis, but surgical resection of symptomatic or enlarged lesions is recommended to rule out the possibility of malignancy and further diagnosis. Genetic testing results revealed the complex genetic alterations in MHL, and it was found that adult MHL can malignantly transform into malignant solitary fibrous tumors. We believe that genome-wide analysis is necessary to determine the unique molecular characteristics of MHL and identify potential targets for therapeutic intervention.

Objective:To investigate the clinicopathological and molecular genetic characteristics of well-differentiated/dedifferentiated liposarcoma (WDLPS/DDLPS) with myxoid-like morphology, and to distinguish them from myxofibrosarcoma (MFS) with similar morphology.Methods:Twenty-nine cases of myxoid-like liposarcoma and 5 cases of MFS were collected from Henan Provincial People′s Hospital, Zhengzhou, China and the First Medical Center of PLA General Hospital, Beijing, China from January 2015 to March 2023. Relevant markers were detected using immunohistochemistry and fluorescence in situ hybridization (FISH). The literature was also reviewed.Results:There were 24 males and 10 females, with ages ranging from 41 to 73 years. The tumor sites included retroperitoneum ( n=17), abdomen ( n=9), lower limbs ( n=5), scrotum ( n=1), upper limb ( n=1) and axilla ( n=1). WDLPS was commonly seen as lipomatoid type (12 cases), while the dedifferentiated components of DDLPS included low-grade (13 cases) and high-grade (2 cases) morphology, with low-high grade myxofibrosarcoma, dermatofibrosarcoma protuberans, and low-grade fibrosarcoma structures. Twenty-nine liposarcomas had various proportions of myxoid-like morphology, while 16 showed various degrees of tumor necrosis. The myxoid-like component showed myxoid pleomorphic liposarcoma (MLPS)-like morphology, lobulated growth, characteristic slender, ramified capillary network,"chicken claw-like"morphology, mucus-rich stroma and lung edema-like morphology. Tumor cells were spindle and oval, with many variable vacuolar lipoblasts. MDM2 gene amplification was detected using FISH and present in all tested cases (29/29). DDIT3 break-apart mutation was not detected, but its cluster amplification was present (24/29). Among the MFS cases, one showed cluster amplification (1/5), but no cases showed break-apart or amplification of MDM2 gene. Conclusions:WDLPS/DDLPS with myxoid-like morphology is most commonly seen in the retroperitoneum and abdominal cavity and mostly harbors DDIT3 break-apart probe amplification, while this amplification is not specific to liposarcoma. For core biopsy specimens or very rare tumors in the limbs, when histology has mucinous stroma and MLPS-like morphology, misdiagnosis of MLPS or other non-lipomatous neoplasms with myxoid morphology should be avoided.