Clinicopathological Study Research Articles

Adenocarcinoma of the rete testis: clinicopathological study of 18 cases with emphasis on MET amplification and a review of the literature.

Knowledge regarding adenocarcinoma of the rete testis (ACRT) is extremely limited due to its scarcity. This study enrolled 18 patients with ACRT from multiple institutions. Clinicopathological and immunohistochemical features were investigated, together with a comprehensive review of 95 previously reported cases. One case was assessed using next-generation sequencing (NGS). The median age of the patient cohort was 54 years (range = 20-69 years), with the majority presenting with a testicular mass (13 of 18); predominantly right-sided (11 of 18). Six patients died within the second year following diagnosis. The morphology of ACRT spans a wide spectrum, including newly identified mucinous carcinoid-like features, with mucous cells floating in mucus and signet-ring cells. Notably, transition from a benign to a malignant rete epithelium was noted in 38.9% of cases (seven of 18). Immunohistochemically, tumour cells most frequently showed strong positivity for CK7 (12 of 16) and CK20 (10 of 17), with occasionally positivity for calretinin (three of 16), WT-1 (two of 17) and PAX-8 (two of 15). According to NGS in a single case, MET was amplified, leading to the patient benefiting from mesenchymal-epidermal transition factor (MET) inhibitors. Furthermore, MET amplification was assessed in 13 cases using fluorescence in-situ hybridisation and detected in two cases (15.4%). No significant correlation between MET amplification and mesenchymal-epidermal transition factor (MET) levels was observed in the cases studied. Primary ACRT is a rare malignant tumour which poses a diagnostic challenge, and is associated with poor prognosis. Cases of ACRT with MET amplification might represent promising candidates for the treatment with MET inhibitors.

Surgical treatment of pancreatic metastases: More appropriate surgical methods based on a clinicopathologic study of 43 patients.

There is no established surgical method for metastatic lesion to the pancreas. In the case of relatively small lesion, we often hesitate to select which surgical method, that is, wedge/partial resection or Whipple/distal pancreatectomy. Moreover, it is debatable whether lymph node dissection is necessary or not. We investigated clinicopathological characteristics in order to resolve the above problems. Forty-three patients underwent pancreatic resection formetastatic tumors in Cancer Institute of the Japanese Foundation for Cancer Research, whose specimens were investigated clinicopathologically. Primary tumors included renal cell carcinoma(RCC), colorectal carcinoma (CRC), and miscellaneous malignancy (MM) in 23, 9, and 11 cases, respectively. Plural metastases in a resected specimen or mpd, i.e., tumor extension into the main pancreatic duct (MPD) was observed in eleven (26%, 11/43) or 9 (21%, 9/43) patients, respectively. Five of 9 mpd cases had more over 2cm intraductal tumor extention from the main metastatic lesion. Lymph node metastasis surrounding the main metastasis was observed in 11 patients (5 CRCs, 5 MMs, and 1 RCC), with a metastatic rate to lymph node of 56% (5/9), 45% (5/11), and 4% (1/23) for CRCs, MMs, and RCCs, respectively. 1) Wedge or partial resection of the pancreas for metastatic tumor should not be easily chosen, because of positive resection margin due to mpd and/or leaving another metastatic lesion. 2) Lymph node dissection is not strictly necessary for the surgical removal of pancreatic metastasis from RCC, whereas this is highly recommended for patients with metastasis from CRC or MM.

Clinicopathological study of a rare neuroectodermal neoplasm of the cranium.

Melanotic neuroectodermal tumor of infancy (MNTI) is a rare, rapidly growing pigmented neoplasm originating from the neural crest. Predominantly affecting infants, it commonly occurs in the head and neck region. MNTI is often locally aggressive with a high recurrence rate. It can be clinically and histologically confused with high-grade malignancies despite being considered benign. We present four cases diagnosed as MNTI through histopathological examination alongside a literature review and would like to study the clinico-radiological findings and histopathological spectrum of this rare entity. This retrospective study (January 2018-March 2024) included cases diagnosed histologically as MNTI. Clinical data, including age, gender, and presentation, were collected. Histological and immunohistochemical analyses were performed using various markers. Four cases (age range, 4-17months; mean, 5.2months) were analyzed. Males were more affected than females (3:1). All presented with scalp swelling. MRI revealed large extra-axial masses with varying contrast enhancement. Histopathology showed biphasic cellular morphology with primitive small round cells and epithelioid cells containing melanin. All cases exhibited brisk mitotic activity and extensive desmoplasia. Immunohistochemically, primitive cells were strongly positive for synaptophysin, while epithelioid cells were positive for cytokeratin and HMB45. Ki-67 indices ranged from 30 to 80%. Follow-up revealed one patient succumbed to sepsis and one had a recurrence. Understanding the clinical and pathological spectrum of MNTI is essential for accurate diagnosis and effective treatment. This study contributes to the existing knowledge by expanding the cohort and enhancing the understanding of this rare tumor.

POLE-mutated uterine carcinosarcomas: a clinicopathologic and molecular study of 11 cases

Uterine carcinosarcomas (UCS) are high-grade biphasic neoplasms with generally poor outcomes. Based on TCGA molecular classification of endometrial carcinomas, the majority of UCS are classified as copy-number high/serous-like (p53 abnormal); however, a small subset represent other molecular subtypes, including those that harbor POLE mutations. We identified 11 POLE-mutated (POLEmut) UCS across three institutions and assessed the clinical, histopathologic, immunohistochemical and molecular features of these tumors. POLEmut UCS occurred in adult women (median age 64 years, range 48 to 79 years) and usually presented as FIGO (2009) clinical stage IA (n = 4) or IB (n=3). Almost all tumors were predominantly carcinomatous (n =10), with most showing endometrioid morphology (n = 7), followed by ambiguous (n=4) and serous (n = 3) histotypes. By immunohistochemistry, 7 tumors showed aberrant or subclonally aberrant expression of p53, 6 of which harbored pathogenic mutations in TP53 by sequencing. Other frequent mutations included PIK3CA (10/11), PTEN (8/11), RB1 (7/11), ARID1A (7/11), ATM (6/11), PIK3RA (5/11) and FBXW7 (4/11). Two tumors demonstrated loss of mismatch repair protein expression and one had subclonal loss. Heterologous differentiation was uncommon and only chondrosarcomatous type (n = 2) was observed. Mean and median follow-up were 24.3 and 14.1 months, respectively (range 1.4 to 61.1 months). Ten patients (91%) had no recurrences or death from disease, though 3 of these had follow-up periods <1 year. One patient, with the subclonal POLE variant, presented with stage IV disease and died 1.4 months after surgery. In conclusion, POLEmut UCS demonstrate unique morphologic and immunohistochemical features compared to their p53-abnormal counterparts and may have significant prognostic differences. Our study supports full molecular classification of UCS. We also raise awareness for potentially assessing POLE mutation allele fraction and clonality in the consideration of classifying a tumor as POLEmut.

Sarcoid Vasculitis in the Skin: A Clinicopathologic Study of 8 Cases With Various Skin Lesions but the Common Unique Cannonball-like Vessel Destruction by Sarcoid Granulomas.

While the skin is a common target organ for sarcoidosis, cutaneous granulomatous vasculitis is rare among patients with sarcoidosis. Due to the lack of detailed studies on cutaneous sarcoid vasculitis, both dermatologists and pathologists remain unfamiliar with this rare but important vasculitic disorder. We clinicopathologically evaluated eight cases with biopsy-proven cutaneous vasculitis and cutaneous sarcoidosis and analyzed morphologic changes in the process of vasculitis for both small vessels and muscular vessels in detail. The various skin lesions ranged from papulonodular erythema, annular erythema, maculopapular erythema, livedo reticularis-like eruptions, erythema nodosum-like lesions, subcutaneous nodules to ulcerative lesions. The extremities were the most frequently affected sites. Bilateral hilar lymphadenopathy with pulmonary sarcoidosis was the most common extracutaneous comorbidity. Skin-limited sarcoidosis was identified in 3 cases. All cases demonstrated a common histopathologic feature with sarcoid granulomas impinging on the target vessels with resultant vessel destruction. Perivascular infiltration of sarcoid granulomas resulted in compression and destruction of small vessels. In muscular arteries and veins, sarcoid granulomas closely attached to the muscular vessel wall, infiltrated the muscular layers and either occupied or penetrated the vessel walls, eventually invading the vascular lumen and replacing the entire muscular layers. The intimal infiltration of sarcoid granulomas resulted in a marked luminal narrowing. The scarcity of reports on cutaneous sarcoid vasculitis may be due to the overlooking or misinterpretation of vascular destruction caused by sarcoid granuloma infiltration as a feature of sarcoid granuloma masses.

Clinicopathological Study of Thyroid Swelling with High Resolution Ultrasonographic Correlation

Clinicopathological Study of Thyroid Swelling with High Resolution Ultrasonographic Correlation

Primary melanoma of the urinary tract: a clinicopathological study of cases and literature review

AimPrimary malignant melanomas in the bladder or urethra are exceedingly rare. Diagnosing these tumours presents substantial challenges due to their close resemblance in gross appearance and histology to urothelial carcinomas.MethodsA...

Clinicopathologic Study of 28 Cases of Tubulocystic Renal Cell Carcinoma: Is It Time to Reclassify It as a Tubulocystic Renal Cell Tumor?

Clinicopathologic Study of 28 Cases of Tubulocystic Renal Cell Carcinoma: Is It Time to Reclassify It as a Tubulocystic Renal Cell Tumor?

Endocervical Adenocarcinoma With Micropapillary Component, a Distinct Histological Subtype Associated With Aggressive Behavior and Poor Prognosis: A Clinicopathologic Study of 10 Patients.

Objective. Endocervical adenocarcinoma (ECA) with a micropapillary component is considered to be associated with aggressive behavior and poor prognosis. So far, only limited studies investigated this histological subtype of ECA in the literature. In this study, we present a clinicopathological analysis of 10 such tumors. Methods. We retrieved ten ECAs with a micropapillary component between January 2014 and July 2023 and analyzed their clinicopathologic features. Results. At diagnosis, nine tumors (90%) were of advanced clinical stage (FIGO stage ≥ IIA), nine tumors (90%) exhibited deep stromal invasion (≥2/3 of the cervix), and three tumors (30%) showed parametrial involvement. Lymphovascular invasion was evident in all tumors (100%), and lymph node metastasis was found in eight tumors (80%). Among the 10 patients, six were alive without disease (60%), one had a recurrent/later metastatic tumor (10%), and three died from the disease (30%). Furthermore, eight tumors were positive for PD-L1 expression (80%), while only one tumor showed HER2 overexpression (10%), and one tumor exhibited p53 mutant-type staining (10%). Conclusion. Endocervical adenocarcinomas with micropapillary components are associated with aggressive clinical behavior and a poor prognosis, which can be found in various conventional histological types of ECAs regardless of the HPV status. The high prevalence of PD-L1 expression suggests that patients with micropapillary ECAs may be good candidates for PD-L1 inhibitor treatment.

A Clinicopathological Study of Scrotal Calcinosis and Literature Review.

Objective. We aimed to investigate the clinicopathological features and pathogenesis of scrotal calcinosis. Methods. Hematoxylin and eosin (HE)-stained slides were performed on 14 patients with scrotal calcinosis, and the clinicopathological characteristics were analyzed together with clinical data. Meanwhile, 81 patients with extrascrotal calcinosis cutis and 7480 patients with epidermoid cysts without calcification in the skin of various parts of the body were collected and analyzed to explore the etiology and pathogenesis of scrotal calcinosis in conjunction with the literature review. Results. All our patients were adult men with a mean age of 38.2 years, with clinical manifestations of multiple scrotal nodules of varying sizes, microscopically characterized by intradermal calcium deposits, of which 3 lesions had a cystic cavity lined with squamous epithelium. Conclusions. Scrotal calcinosis is a rare benign disease that presents clinically as single or multiple hard nodules in the scrotum, usually asymptomatic, and it is histopathologically characterized by intradermal calcium deposition. There is still controversy as to whether it is idiopathic. We believe that scrotal calcinosis is not idiopathic and originates from epidermoid cysts. Prolonged local compression or injury may be one reason for the development of calcification, and perhaps there are other unknown factors contributing to the development of the disease. Surgical excision is the main treatment for this disease with satisfactory therapeutic effectiveness.

Clinicopathological findings and etiological characterization in caprine gangrenous mastitis

Gangrenous mastitis ranks among the most economically significant diseases affecting small ruminants. In the present study, along with clinicopathological studies, the etiological characterisation and the contribution of various virulence factors of caprine gangrenous mastitis was studied. Staphylococcus aureus with colony count ranging from 106 to 108 CFU/mL has been identified as the etiological agent in 15 gangrenous mastitis affected goats based on cultural isolation, biochemical characteristics and molecular confirmation. Haematological and serum biochemical analysis was carried out in the affected goats which revealed leucocytosis with thrombocytopenia and hypoproteinemia. Phenotypic identification of antibiotic resistance revealed significantly high resistance to enrofloxacin, sulpha-trimethoprim, tetracycline, and gentamicin whereas the antibiotics cefoperazone, ceftriaxone- tazobactam and amoxicillin clavulanate showed least resistance. Toxin genes lukMF, and hla were detected in 66.7 per cent and 60 per cent of the isolates respectively. Antibiotic resistant genes blaZ (13.3 %), tetM (20 %), sul1 (13.3 %), mecA (80 %) and biofilm forming genes like icaA (26.6 %) icaD (40 %) were also detected in the S. aureus isolates. Majority of the isolates revealed significantly higher antibiotic resistance along with toxin genes and all the isolates showed biofilm formation. Biofilm forming ability of S. aureus plays a crucial role in its virulence whereas, antimicrobial resistance has a significant role in potentiating the virulence of pathogen.

Intracapillary monoclonal IgM deposits disease with massive pseudothrombi: A clinicopathologic study of 4 cases and literature review.

Intracapillary monoclonal IgM deposits disease (ICMDD) has long been considered a hallmark of Waldenström macroglobulinemia (WM) nephropathy. Intracapillary immunoglobulin thrombi are the characteristic features of cryoglobulinemic glomerulonephritis. Here, we reported 4 cases of ICMDD with massive pseudothrombi but without WM or cryoglobulinemia. We retrospectively analyzed the clinical and pathologic features of patients diagnosed with ICMDD with massive pseudothrombi. A total of 4 patients (2 men and 2 women) aged 62 to 73 years were enrolled in this study. Microscopic hematuria, edema, and renal insufficiency were present in all patients, along with low serum C3 and C4 in 2 patients. Hematologic examination showed abnormal serum free light chain ratios in all patients and high levels of serum IgM in 3 patients. IgM-κ monoclonal band was identified by serum immunofixation electrophoresis in 3 patients. One patient was diagnosed with small B-cell lymphoma by bone marrow aspiration. Renal biopsy specimen showed massive periodic acid-Schiff-positive hyaline thrombi in the glomerular capillary lumens and also less mesangial, subendothelial, and subepithelial deposits on light microscopy. Immunofluorescence indicated positive staining for IgM (++) and κ light chain staining in the glomerular capillary lumens, capillary walls, and mesangium in all patients. By electron microscopy, the glomerular capillary lumens were filled with homogeneous high-electron-dense deposits without substructure. Two patients were treated with prednisone combined with cyclophosphamide, and 2 received plasma cell-targeted chemotherapy. One patient achieved partial renal remission. Intracapillary monoclonal IgM deposits disease is a rare disease and not always related to WM. Most patients have IgM monoclonal immunoglobulinemia; renal biopsy specimens mainly show a large number of pseudothrombi in the glomerular capillary lumens. Cyclophosphamide is effective in some patients.

A Clinicopathologic Study of 1598 Ultrasound-Guided Needle Prostate Biopsies and Trends in Prostate Cancer Over a 14-Year Period

BackgroundProstate cancer manifests in various forms, ranging from occult and localized to metastatic disease. Analyzing prostate biopsies offers insights into histopathological characteristics, enhancing disease understanding and management. MethodsThis 14-year study reviewed ultrasound-guided needle prostate biopsies, collecting data via questionnaires and medical records, focusing on Gleason group, tumor involvement percentage, and predicted cancer stage. A comparative analysis across 2 distinct 7-year intervals was conducted. Statistical analyses included the Kolmogorov–Smirnov test, chi-square test, Fisher's exact test, and Analysis of Covariance, all performed using SPSS software. ResultsAmong 1,598 biopsies, 624 cases of adenocarcinoma were identified. Malignancy incidence significantly correlated positively with age, prostate-specific antigen (PSA), and PSA density (PSAD), and inversely with prostate volume and the free-to-total PSA ratio (%fPSA). Notably, 30.8% of malignancies were classified as Gleason groups 4 or 5, displaying significantly higher PSA levels. Patients with prior transurethral resection of the prostate exhibited increased malignancy rates and higher Gleason groups. Diagnostic accuracy, measured by Area Under the Curve, was 0.719 for PSA, 0.730 for %fPSA, and 0.817 for PSAD. The later phase of the study showed higher cancer detection, lower PSA levels, and a greater incidence of higher Gleason groups despite a lower predicted stage. ConclusionThe prevalence of higher Gleason groups was similar to other studies. PSAD demonstrated greater diagnostic reliability than PSA alone. Additionally, higher malignancy rates and Gleason groups were observed in patients with prior transurethral resection of the prostate. The increase in cancer detection rates during the second period likely indicates improved biopsy candidate selection.

Large cell neuroendocrine carcinoma in pancreatoblastoma with TP53 and SMAD4 mutations: a clinicopathologic study of a rare entity

Abstract Pancreatoblastoma, a rare pancreatic tumor, exhibits diverse differentiation pathways, including acinar, ductal, and neuroendocrine lineages, often with distinct squamoid nests [3]. We present a notable case of pancreatoblastoma coexisting with large cell neuroendocrine carcinoma in a 10-year-old boy, presenting with abdominal discomfort, weight loss, and lesions in the pancreas, spleen, and liver visible on imaging. A liver biopsy revealed a poorly differentiated carcinoma with neuroendocrine features, while a splenic biopsy showed acinar cell differentiation, raising possible diagnoses of pancreatoblastoma or acinar cell carcinoma. Subsequent surgical resection after chemotherapy revealed diverse components within the pancreatoblastoma, including well-differentiated acinar and neuroendocrine cells, squamoid nests, and a high-grade neuroendocrine carcinoma. Genetic analysis detected pathogenic variants in TP53 and SMAD4, rarely found in pancreatoblastomas. This juxtaposition of large cell neuroendocrine carcinoma and pancreatoblastoma suggests a potential evolution from well-differentiated neuroendocrine tumors to poorly-differentiated carcinomas within pancreatoblastomas.

Large-cell Basaloid Adenocarcinoma of the Lung: A Clinicopathologic Study of 12 Cases of a Distinctive Form of Lung Cancer Often Mistaken for Large-cell Neuroendocrine Carcinoma.

A distinctive form of lung adenocarcinoma that closely mimics large-cell neuroendocrine carcinoma is described. The tumors arose in 6 women and 6 men aged 46-86 years (mean=58.4). They presented as peripheral subpleural masses measuring 2-12cm (mean=6.5cm). Histologically they were characterized by islands or anastomosing and serpiginous strands of large, atypical cells showing striking peripheral palisading of nuclei, with high mitotic activity and prominent comedo-like areas of necrosis. Because of the striking resemblance to neuroendocrine tumors, some of the cases were initially diagnosed as large-cell neuroendocrine carcinoma despite the absence of neuroendocrine markers. Immunohistochemistry showed positivity of the tumor cells for TTF1 and napsin-A, and negative staining for p40. The tumors were also uniformly negative for multiple neuroendocrine markers, including chromogranin, synaptophysin, CD56, and INSM1. Electron microscopy performed in 2 cases was negative for membrane-bound dense core neurosecretory granules. Pathogenic alterations were detected in 5 of 8 tumors tested by next-generation sequencing. Point mutations in KRAS and TP53 were identified in 5 patients. Low-level amplification of GNAS, KIT, and FGFR1 was present in 2 patients. No RB1 mutations were identified. Clinical follow-up in 10 cases showed that 2 patients died of their tumors, 2 experienced distant metastases, and 6 were alive and well from 1 to 13 years after diagnosis (median=7.1y). Large-cell basaloid adenocarcinoma is an unusual variant of lung cancer that is easily confused with large-cell neuroendocrine carcinoma. Awareness of this unusual variant of lung adenocarcinoma is important for treatment and prognosis and for avoiding misdiagnosis.

P-36724572-886 - Clinicopathological Study of Orofacial Tumors in Iraq

P-36724572-886 - Clinicopathological Study of Orofacial Tumors in Iraq

Clinicopathological Study of Mucormycosis at Varied Sites During the COVID-19 Pandemic.

Mucormycosis, also known as black fungus, is a rare but serious fungal infection caused by mucor that belongs to Zygomycotic species. Mucor is characterized by non-septate, irregularly wide hyphae with right-angle branching. Mucor can infect different systems of the body and manifest differently depending on the location of the infection, which includes pulmonary, gastrointestinal, rhino-cerebral, and cutaneous. The study aims to analyze the incidence, clinical history, and microscopic features associated with mucormycosis in the COVID-19 pandemic at our institute. This is a prospective study conducted in the Department of Pathology for three years from March 2020 to April 2022. The samples were collected from different clinical departments mostly from Surgery and Radiology. These samples were fixed in 10% formalin, processed,stained with hematoxylin and eosin(H&E) and were analysed. A total of 69 cases were included in the study. The age range was 25-80 years and male preponderance was seen with an M:F ratio of 2.6:1. Diabetes was the most common risk factor seen in 53 (77%) casesfollowed by post-COVID-19 status in 49 (71%) cases. The most common site was paranasal sinuses (58, 84%) followed by orbit (eight, 11%) and two (2.8%) cases each of lung and bone. Fifty (72.4%)cases showed necrosis and 10 (14.5%)cases showed granulomatous inflammation. Angioinvasion was seen in 27 (39%) cases, bony invasion was seen in 26 (37.6%) cases and perineural invasion was seen in one (1.4%) case. We had three (4.3%) cases of mixed fungal infection (mucor and Aspergillus). This study describes the clinical site of presentation and histopathological features of mucormycosis.

Granulomatous panuveitis following prolonged silicone oil tamponade - A Clinicopathological study.

An enucleated specimen of a silicone oil-filled globe, showing migration of oil globules into the intraretinal, choroidal, and ciliary body areas, surrounded by multinucleated giant cells suggestive of panuveitis on histopathological evaluation, was reported.

Clear Cell Adenocarcinoma of the Urinary Tract Primary to the Renal Pelvis: A Multi-institutional Clinicopathologic and Molecular Study of Five Patients.

Clear cell adenocarcinoma (CCA) of the urinary tract is a rare malignancy and tumors involving the renal pelvis are notably sparse in the literature, with only 5 other patients reported. We present 5 patients, 4 women, and 1 man, with CCA of the renal pelvis. The age at presentation ranged from 29 to 81 years. The tumor size ranged from 4.5 to 8.0 cm. Tumors exhibited shared morphologic and immunohistochemical features with CCA of the female genital tract and those originating in the bladder and urethra, including cells with large nuclei, prominent nucleoli, nuclear hobnailing, and scant clear cytoplasm. Common immunohistochemical findings included reactivity for PAX8, CK7, HNF1β, and Napsin-A. One of the tumors arose in the background of a mixed epithelial and stromal tumor. Another tumor occurred in a renal allograft and tumor cells were positive for the BK virus, demonstrated by SV40 immunohistochemistry. All tumors were negative for TFE3 and TFEB rearrangement and lacked TERT alterations. Follow-up was limited with no recurrence in 4 patients at a maximum of 20 months follow-up and 1 patient died of an unrelated cause at 25 months of follow-up. Next-generation sequencing analysis of all 5 CCAs revealed mutations within genes implicated in DNA damage repair and chromatin remodeling pathways, including ATM, BRCA1, BRCA2, ARID1A, DICER1, SMAD4, NOTCH1, and MYC amplification. These molecular findings underscore the dysregulation of fundamental cellular processes essential for genomic integrity maintenance.

Clinicopathological study of 24 cases of monkeypox virus infection-related rashes

Objective: To investigate the clinicopathological characteristics of rashes in monkeypox patients through a series of skin biopsies, and examine their pathological features and the most effective tests. Methods: Patients with monkeypox virus infection admitted to Beijing Ditan Hospital from June to August 2023 were identified. Among them, 24 patients underwent skin biopsies for clinical pathological study that were included in this study. Clinical information, rash pictures, and nucleic acid test results were analyzed using histopathology, immunohistochemistry, RNAscope® hybridization and electron microscopy. Results: All 24 patients were male, including 14 patients with concurrent human immunodeficiency virus infection. Their average age was (32.3±5.4) years. The nucleic acid test confirmed monkeypox virus infection. The clinical feature of monkeypox rashes was solitary rather than clustered distribution, with rashes occurring in similar phase, distinguishing it from herpesvirus. The rashes in these patients were mostly scattered, with an average of (13.0±11.8) rashes, and most commonly present in the perineum, face, limbs, and trunk. The three main pathological features of these rashes were ballooning degeneration of the epidermal spinous cell layer, the characteristic intra-cytoplasmic Guarnieri's bodies and significant infiltration of inflammatory cells in whole dermal layer. Immunohistochemistry, RNAscope® hybridization, and electron microscopy can all effectively detect the monkeypox virus. Electron microscopy showed viral replication in various types of skin cells. Conclusions: The study describes the pathological features of monkeypox virus rashes. Pathological examination of skin biopsy samples is helpful to diagnose these rashes. The study suggests that the monkeypox virus has a unique epitheliotropic affinity and can infect various types of cells in the skin.