[Discussion on pathological diagnosis of vascular diseases based on ISSVA classification].

The diagnosis of vascular diseases is not only about distinguishing neoplastic or non-neoplastic lesions, but also focusing more on emphasizing the essence of the disease, namely the presence or absence of endothelial cell proliferation, and further to distinguishing true hemangioma tumors or vascular malformation. This article is based on the International Society for the Study of Vascular Anomalies (ISSVA) classification, which is widely used in clinical practice, and discusses the related pathological diagnosis issues of vascular diseases.

[Clinicopathological and genetic characteristics of common lymphatic malformations in superficial soft tissues].

Objective: To investigate the clinicopathological features, classification, and genetic characteristics of common lymphatic malformation (CLM) in superficial soft tissue. Methods: A retrospective study of 110 patients with the diagnosis of CLM at the Henan Province People's Hospital, China from August 2019 to August 2022 was performed. The clinicopathological features, relevant immunohistochemical (IHC) staining results, and fluorescence quantitative PCR of PIK3CA mutation were analyzed, and patients were followed up. Results: Among the 110 CLM patients, there were 53 males and 57 females; 65 cases (65/110, 59.1%) were first detected when the patients were≤2 years old. The most common location was the head and neck in 41 cases (41/110, 37.3%). Clinically, 102 cases (102/110, 92.7%) were solitary, 83 cases (83/110, 75.5%) were skin-colored, 69 cases (69/110, 62.7%) had indistinct borders, and 10 cases (10/110, 9.1%) had diffuse and severe macroscopic manifestations. There were 52 macrocystic type (52/110, 47.3%), 23 microcystic type (23/110, 20.9%), and 35 combined type (35/110, 31.8%). The macrocystic CLM presented as soft, translucent masses with large cystic cavities on the cut surface, and histologically they were composed of large, irregularly dilated channels that were thicker with irregular smooth muscle and lymphocytic infiltration. Microcystic CLM showed wartlike projections or translucent blisters on the skin, with small honeycomb structures on the cut surface, and histologically consisted of round or angular dilated small lymphatic vessels with little or no smooth muscle. The combined CLM had both macrocystic and microcystic morphologies. IHC staining showed that the lymphatic endothelial cells were positive for LYVE-1, D2-40, PROX1, CD31, and VEGFR3 but negative for CD34; in the macrocystic and combined CLM vessel walls were positive for SMA. Eight of 13 CLM had PIK3CA mutation. All patients were followed up, and 24 (24/110, 21.8%) had relapses, which more frequently occurred in combined type, followed by microcystic type. Conclusions: CLM is a congenital vascular malformation composed of dilated, abnormal lymphatic channels, with PIK3CA mutation. There are significant differences in clinicopathological characteristics among the different types. Since microcystic and combined CLM are prone to recurrence, accurate pathological subtyping is necessary to guide treatment and to predict prognosis.

[Intraductal carcinomas of the salivary glands: a clinicopathological and molecular genetic analysis of twenty-seven cases].

Objective: To investigate the clinicopathological features, molecular genetic features, and differential diagnosis of intraductal carcinomas (IDC) of the salivary glands. Methods: Twenty-five cases of salivary gland IDC diagnosed at the Department of Oral Pathology, Shanghai Ninth People's Hospital and two cases from Department of Pathology, Henan Provincial People's Hospital, Zhengzhou, China from January 2008 to July 2023 were collected. Their clinical and pathological features were analyzed retrospectively. Fluorescence in situ hybridization and Sanger sequencing were performed. The patients were followed up and related literatures were reviewed. Results: There were 27 patients with IDC, including 15 males and 12 females, ranging in age from 20.0 to 80.0 years (mean 55.9 years). Clinically, the tumor often presented as a painless mass with a tumor diameter of 1.0-3.0 cm (mean 2.0 cm). All patients received surgical treatment. Twenty patients were followed up. One of them (1/20) died of lung cancer, while the rest survived without tumor recurrence. Histologically, IDC were classified as: intercalated (63.0%, 17/27), apocrine (25.9%, 7/27), oncocytic (7.4%, 2/27) and mixed (3.7%, 1/27) types. Intercalated tumors showed positive S-100 and negative androgen receptor (AR) immunoreactivity. Ki-67 proliferation index was low (about 1%-5%). Nine cases had the RET gene disruption, and 2 cases showed the BRAF V600E mutation. Apocrine tumors showed strong AR immunoreactivity but no S-100 immunoreactivity. Ki-67 proliferation index was high (about 10%-60%), and the RET gene rupture was detected in 1 case. Oncocytic tumors were similar to that of intercalated type in 2 cases, and RET gene disruption was detected in the both cases. Mixed tumors showed histologic features of oncocytic and apocrine patterns and harbored the RET gene disruption. Conclusions: IDC is a rare low-grade malignant tumor of the salivary gland and easily confused with other salivary gland tumors with similar morphology. Molecular testing is helpful for its differential diagnosis.

[Well-differentiated/dedifferentiated liposarcoma associated with myxoid-like morphology: a clinicopathological and molecular genetic characteristics analysis of 34 cases].

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.

[Application and evaluation of artificial intelligence TPS-assisted cytologic screening system in urine exfoliative cytology].

Objective: To explore the application of manual screening collaborated with the Artificial Intelligence TPS-Assisted Cytologic Screening System in urinary exfoliative cytology and its clinical values. Methods: A total of 3 033 urine exfoliated cytology samples were collected at the Henan People's Hospital, Capital Medical University, Beijing, China. Liquid-based thin-layer cytology was prepared. The slides were manually read under the microscope and digitally presented using a scanner. The intelligent identification and analysis were carried out using an artificial intelligence TPS assisted screening system. The Paris Report Classification System of Urinary Exfoliated Cytology 2022 was used as the evaluation standard. Atypical urothelial cells and even higher grade lesions were considered as positive when evaluating the recognition sensitivity, specificity, and diagnostic accuracy of artificial intelligence-assisted screening systems and human-machine collaborative cytologic screening methods in urine exfoliative cytology. Among the collected cases, there were also 1 100 pathological tissue controls. Results: The accuracy, sensitivity and specificity of the AI-assisted cytologic screening system were 77.18%, 90.79% and 69.49%; those of human-machine coordination method were 92.89%, 99.63% and 89.09%, respectively. Compared with the histopathological results, the accuracy, sensitivity and specificity of manual reading were 79.82%, 74.20% and 95.80%, respectively, while those of AI-assisted cytologic screening system were 93.45%, 93.73% and 92.66%, respectively. The accuracy, sensitivity and specificity of human-machine coordination method were 95.36%, 95.21% and 95.80%, respectively. Both cytological and histological controls showed that human-machine coordination review method had higher diagnostic accuracy and sensitivity, and lower false negative rates. Conclusions: The artificial intelligence TPS assisted cytologic screening system has achieved acceptable accuracy in urine exfoliation cytologic screening. The combination of manual screening and artificial intelligence TPS assisted screening system can effectively improve the sensitivity and accuracy of cytologic screening and reduce the risk of misdiagnosis.

[Primary synovial sarcoma of lung: a clinicopathological analysis of 12 cases].

Objective: To investigate the clinicopathological features, immunophenotype, molecular features and differential diagnosis of primary synovial sarcoma of the lung (PSSL). Methods: Twelve cases of PSSL were collected at Henan Provincial People's Hospital, during May 2010 and April 2021, and their clinicopathological parameters were summarized. SS18-SSX, H3K27Me3, and SOX2 were added to the original immunomarkers to evaluate their diagnostic value for PSSL. Results: The age of 12 patients when diagnosed ranged from 32 to 75 years (mean of 50 years). There were 7 males and 5 females, 2 left lung cases and 10 right lung cases. Of the 6 patients who underwent surgical resection, five cases were confined to lung tissue (T1), one case had mediastinal invasion (T3), two cases had regional lymph node metastasis (N1), and none had distal metastasis. Microscopically, 11 cases showed monophasic spindle cell type and one case showed biphasic type composed of mainly epithelial cells consisting of cuboidal to columnar cells with glandular and cribriform structures. It was difficult to make the diagnosis by using the biopsy specimens. Immunohistochemistry (IHC) showed CKpan expression in 8 of 12 cases; EMA expression in 11 of 12 case; TLE1 expression in 8 of 12 cases; S-100 protein expression in two of 12 cases; various expression of bcl-2 and vimentin in 12 cases, but no expression of SOX10 and CD34 in all the cases. The Ki-67 index was 15%-30%. The expression of SS18-SSX fusion antibody was diffusely and strongly positive in all 12 cases. SOX2 was partially or diffusely expressed in 8 of 12 cases, with strong expression in the epithelial component. H3K27Me3 was absent in 3 of 12 cases. SS18 gene translocation was confirmed by fluorescence in situ hybridization (FISH) test in all 12 samples. Six cases underwent surgery and postoperative chemotherapy, while the other six cases had chemotherapy alone. Ten patients were followed up after 9-114 months, with an average of 41 months and a median of 26 months. Five patients survived and five died of the disease within two years. Conclusions: PSSL is rare and has a broad morphological spectrum. IHC and molecular tests are needed for definitive diagnosis. Compared with current commonly used IHC markers, SS18-SSX fusion antibody has better sensitivity to PSSL, which could be used as an alternative for FISH, reverse transcription-polymerase chain reaction or next generation sequencing in the diagnosis of PSSL.

[Glomuvenous malformation: a clinicopathological analysis of 31 cases].

Objective: To investigate the clinicopathological features of glomuvenous malformation (GVM). Methods: Thirty-one cases of GVM diagnosed at the Henan Provincial People's Hospital from January 2011 to December 2021 were collected. Their clinical and pathological features were analyzed. The expression of relevant markers was examined using immunohistochemistry. The patients were also followed up. Results: There were 16 males and 15 females in this study, with an average age of 11 years (range, 1-52 years). The locations of the disease included 13 cases in the limbs (8 cases in the upper limbs, 5 cases in the lower limbs), 9 cases in the trunks, and 9 cases in the foot (toes or subungual area). Twenty-seven of the cases were solitary and 4 were multifocal. The lesions were characterized by blue-purple papules or plaques on the skin surface, which grew slowly. The lumps became larger and appeared to be conspicuous. Microscopically, GVM mainly involved the dermis and subcutaneous tissue, with an overall ill-defined border. There were scattered or clustered irregular dilated vein-like lumens, with thin walls and various sizes. A single or multiple layers of relatively uniform cubic/glomus cells were present at the abnormal wall, with scattered small nests of the glomus cells. The endothelial cells in the wall of abnormal lumen were flat or absent. Immunohistochemistry showed that glomus cells strongly expressed SMA, h-caldesmon, and collagen IV. Malformed vascular endothelial cells expressed CD31, CD34 and ERG. No postoperative recurrence was found in the 12 cases. Conclusions: GVM is an uncommon type of simple venous malformation in the superficial soft tissue and different from the classical glomus tumor. Morphologically, one or more layers of glomus cells grow around the dilated venous malformation-like lumen, which can be combined with common venous malformations.

[Primary adrenal NK/T cell lymphoma: a clinicopathologic analysis of six cases].

Objective: To investigate the clinicopathologic features of primary adrenal NK/T cell lymphoma (PANKL). Methods: Six cases of PANKL were collected at Henan Provincial People's Hospital from January 2000 to December 2021. The clinicopathologic features including morphology, immunophenotype, treatment and prognosis were retrospectively analyzed, and relevant literature was reviewed. Results: There were two males and four females. The median age was 63 years (ranged from 57 to 68 years). The tumors involved bilateral adrenal glands in 4 cases and unilateral adrenal gland in 2 cases. The main clinical symptom was low back pain without obvious cause. Serum lactate dehydrogenase (LDH) is elevated in five cases. The imaging feature was rapidly enlarging mass initially confined to unilateral/bilateral adrenal glands. Morphologically, the lymphoid cells were mainly medium-sized with a diffuse growth pattern. Coagulative necrosis and nuclear fragmentation were common. Angioinvasion was seen. Immunophenotypically, the neoplastic cells were positive for CD3, CD56 and TIA-1 while CD5 was negative in 5 cases. All cases were positive for EBER by in situ hybridization with more than 80% proliferative activity by Ki-67. Four cases received chemotherapy, one case underwent surgery, and one case underwent surgery with chemotherapy. Follow-up was done in 5 cases; one case was lost to follow-up. Three patients died with a median survival of 11.6 months (3-42 months). Conclusions: PANKL is rare with highly aggressive clinical presentation and poor prognosis. Accurate diagnosis entails correlation of histomorphology, immunohistochemistry, EBER in situ hybridization and clinical history.

[Clinicopathological and molecular genetic characteristics of nodular fasciitis in unusual sites].

Objective: To study the clinicopathological, immunophenotypic and molecular genetic characteristics of nodular fasciitis (NF) in unusual sites. Methods: A total of 50 cases of NF diagnosed between January 2015 and January 2021 were reviewed in the Department of Pathology, Henan Provincial People's Hospital, and the clinical and pathologic data were analyzed. Among them, 14 cases from unusual sites were included in this study. Immunohistochemical (IHC) staining was used to detect the expression of related proteins, and fluorescence in situ hybridization (FISH) was used to detect the breakage of the USP6 gene. Results: There were seven males and seven females in the 14 NF respectively. The lesions were located in the extremities, perineum, breast, wrist joints, the gap between lumbar vertebra 4/5, and in eight cases there was involvement of unusual tissues (six cases in skeletal muscle, one case in nerve root, and one case was intravascular). The tumor boundary was unclear with infiltrating growth. Spindle-shaped myofibroblasts were arranged in bundles or chaotically, with mild pleomorphic, small nucleoli and various mitotic figures. The tumor stroma showed collagenization to myxoid degeneration with erythrocyte extravasation and infiltration of inflammatory cells. IHC staining showed that the spindle cells expressed SMA focally or partially, and p16 diffusely and strongly. FISH showed that 12 of 14 cases had USP6 gene breakage, and two of them occurred in the intrathoracic skeletal muscle with the red signal amplification of USP6 gene. Conclusions: NF in unusual sites shows similar clinicopathological and genetic characteristics to classic NF, but the tumor mostly has infiltrating borders, non-specific and strong expression of p16, and USP6 red signal amplification. The pathological diagnosis of NF in rare sites should be highly vigilant.

[Fibrous hamartoma of infancy: a clinicopathological and molecular genetic analysis of 33 cases].

Objective: To investigate the clinicopathological features, immunophenotypic and molecular genetic characteristics and differential diagnosis of fibrous hamartoma of infancy (FHI). Methods: Thirty-three cases of surgically removed FHI were collected from the Department of Pathology, Henan Provincial People's Hospital from October 2011 to December 2020, the clinical and pathologic data with follow-up were collected and analyzed. Next-generation sequencing (NGS) and quantitative real time polymerase chain reaction (q-PCR) were used to study the molecular genetics. Results: The FHI cases occurred in 21 males and 12 females (mean age 16.7 months, range 6 months to 6 years). The sites included trunk (n=21), limb (n=11), and neck (n=1). All patients had painless solitary superficial soft tissue masses, the size was 1.5-9.0 cm (mean 3.8 cm). Microscopically, they were composed of mature adipose tissue, fibroblast/myofibroblast bundle and primitive mesenchymal cells in different proportions; giant cell fibroblastoma-like areas were seen in 14 cases. Immunohistochemistry showed variable expression of EGFR in the spindle cells and primitive mesenchymal components. In most cases, the spindle cells were positive for CD34 and SMA; giant cell fibroblastoma-like areas were strongly positive for CD34; and S-100 protein was expressed by adipocytes in all cases. Ki-67 labeling index ranged 1%-5%. There were recurrent somatic EGFR exon 20 insertion/duplication mutations in six cases tested by NGS, and there were three different mutation types: p.Asn771_His773dupAsnProHis, p.Pro772_His773insProProHis, and p.His773_Val774insThrHis. All the above 6 and another 15 tested cases showed EGFR exon 20 insertion/duplication mutations by q-PCR. Conclusions: FHI is a rare benign fibroblast/myofibroblast tumor. The characteristic histologic feature is organoid triphasic morphology, and the molecular feature is somatic mutation of EGFR exon 20 (insertion/duplication).

[Clinicopathological features of mature T/NK cell lymphoma with aberrant CD20 or CD79α expression].

Objective: To investigate the clinicopathological characteristics and prognosis of mature T/NK cell lymphomas with aberrant CD20 or CD79α expression. Methods: A retrospective analysis of 641 cases of mature T/NK cell lymphoma diagnosed from January 2014 to December 2020 was performed, and 14 cases of CD20-positive and one case of CD79α-positive mature T/NK-cell lymphoma were identified. Histological examination, immunohistochemical characterization, in situ hybridization for Epstein-Barr virus encoded early RNA (EBER), and PCR testing for immunoglobulin and T cell receptor (TCR) gene rearrangements were performed. Clinicopathological characteristics of these lymphomas were analyzed. Results: There were 13 males and 2 females, with a median age of 56 years. There were 8 cases of peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS), 3 cases of extranodal NK/T-cell lymphoma, nasal type (ENKTCL), 2 cases of monomorphic epitheliotropic intestinal T-cell lymphoma (MEITL) and 2 cases of angioimmunoblastic T-cell lymphoma (AITL). Twelve cases were stage Ⅲ or Ⅳ lymphomas. The prognosis was overall poor. The histology, immunophenotype and TCR gene rearrangement were not significantly different from the corresponding types of lymphoma. Ki-67 proliferation index was over 70% in all cases. The expression of CD20 or CD79α was weak and heterogeneous. All 15 case of Ig gene rearrangement were polyclonal. Conclusions: Mature T/NK cell lymphoma with abnormal expression of CD20 or CD79α is rare, commonly found in advanced stage, and associated with poor prognosis. The expression of CD20 or CD79α in these cases is weaker than the corresponding mature T/NK cell lymphomas, while its proliferation index is higher. Histomorphology, extensive immunoprofiling and molecular detection are required for accurate diagnosis.

[Clinicopathological features and BRAF V600E and MYD88 L265P mutation status of nodal marginal zone lymphoma].

Objective: To investigate the clinicopathological features as well as BRAF V600E and MYD88 L265P mutation status of nodal marginal zone B cell lymphoma (NMZL). Methods: Thirty-two cases of NMZL were diagnosed from September 2009 to February 2021 at the Henan Provincial People's Hospital and Peking University School of Basic Medical Sciences. The clinicopathologic characteristics were obtained and analyzed. BRAF V600E and MYD88 L265P mutation status were identified using PCR and Sanger sequencing, respectively. Results: There were 20 males and 12 females patients with a median age of 69 years (ranging 36-82 years). The most prevalent clinical manifestation was multiple lymph nodes enlargement in head and neck (22/32, 68.8%), followed by inguinal (12/32, 37.5%), axillary (11/32, 34.4%), mediastinum (5/32, 15.6%) and retroperitoneal lymph nodes (4/32, 12.5%). Most of the patients were in Ann Arbor stage Ⅰ/Ⅱ (21 cases). The morphologic features included diffuse (24/32, 75.0%), nodular (5/32, 15.6%), interfollicular (2/32,6.3%) and perifollicular (1/32,3.1%) types. The tumor cells showed monocyte-like, centrocyte-like, small lymphocyte-like and plasma cell-like differentiation. Immunophenotyping revealed diffuse expression of CD20 in all tumor cells, whereas CD43 (11/32, 34.4%), bcl-2 (20/32, 62.5%), MNDA (13/32, 40.6%) and CD5 (2/32, 6.3%) were partially expressed. Ki-67 proliferation index varied from 10% to 40%. BRAF V600E mutation was found in two cases (2/32, 6.3%), but MYD88 L265P mutation was not detected. Eighteen patients survived and three died at the end of follow-up period which ranged 6 to 110 months. Conclusions: The morphologic features of NMZL varies across individuals, it should be differentiated from various B-cell lymphomas; however immunological biomarkers with high specificity for NMZL are still lacking. No MYD88 L265P mutation is found in NMZL. Some cases may harbor BRAF V600E mutation and yet the prevalence remains indeterminate; further researches are warranted.

[Clinicopathological features of congenital hemangioma: a study of 40 cases].

Objective: To investigate the clinical and pathologic features, diagnosis and differential diagnosis of congenital hemangioma (CH). Methods: Forty cases of CH were diagnosed from January 2017 to December 2020 in Henan Provincial People's Hospital. The clinical and pathological and immunohistochemical data were analyzed, with review of literature. Results: There were 24 male and 16 female patients. The lesions were located in the head, neck (11 cases), limbs (14 cases), and trunk (15 cases). The clinical manifestations were congenital painless plaques or masses, the larger ones protruded on the skin surface, mostly dusky purple or bright red, with surrounding white halos. Under low magnification, the tumor was lobular and well demarcated, composed of neo-microvascular lumen of different sizes. The vascular endothelial cells were cuboidal or hobnail in appearance, forming stellar drainage vessels within the lobules. Extra-medullary hematopoiesis was seen in one case of rapidly involuting CH; there were different number of tortuous and dilated vascular lumen between the lobular structures, and some non-involuting CH cases were vascular malformations, which were devoid of lobulated structures. Immunohistochemistry showed that endothelial cells were strongly positive for CD31, CD34 and ERG, while D2-40 and GLUT-1 were negative. Conclusions: CH is a benign congenital vascular tumor with characteristic lobulated growth and abnormal blood vessels in the stroma. Pathological diagnosis often needs to be differentiated from infantile hemangioma, pyogenic granuloma, kaposiform hemangioendothelioma and vascular malformation.