Microinvasion in hepatocellular carcinoma: predictive factor and application for definition of clinical target volume for radiotherapy.

BACKGROUND: To investigate the correlation between microinvasion and various features of hepatocellular carcinoma (HCC), and to clarify the microinvasion distance from visible HCC lesions to subclinical lesions, so as to provide clinical basis for the expandable boundary of clinical target volume (CTV) from gross tumor volume (GTV) in the radiotherapy of HCC. METHODS: HCC patients underwent hepatectomy of liver cancer in our hospital between July 2019 and November 2021 were enrolled. Data on various features and tumor microinvasion distance were collected. The distribution characteristics of microinvasion distance were analyzed to investigate its potential correlation with various features. Tumor size compared between radiographic and pathologic samples was analyzed to clarify the application of pathologic microinvasion to identify subclinical lesions of radiographic imaging. RESULTS: The average microinvasion distance was 0.6 mm, with 95% patients exhibiting microinvasion distance less than 3.0 mm, and the maximum microinvasion distance was 4.0 mm. A significant correlation was found between microinvasion and liver cirrhosis (P = 0.036), serum albumin level (P = 0.049). Multivariate logistic regression analysis revealed that HCC patients with cirrhosis had a significantly lower risk of microinvasion (OR = 0.09, 95%CI = 0.02 ~ 0.50, P = 0.006). Tumor size was overestimated by 1.6 mm (95%CI=-12.8 ~ 16.0 mm) on radiographic size compared to pathologic size, with a mean %Δsize of 2.96% (95%CI=-0.57%~6.50%). The %Δsize ranged from - 29.03% to 34.78%. CONCLUSIONS: CTV expanding by 5.4 mm from radiographic GTV could include all pathologic microinvasive lesions in the radiotherapy of HCC. Liver cirrhosis was correlated with microinvasion and were independent predictive factor of microinvasion in HCC.

Pearls and pitfalls in the diagnosis of small oral biopsies.

Pathologic processes affecting the oral and maxillofacial region include a heterogenous group of diseases with widely variable biologic behaviors. Proper patient management begins with the establishment of an accurate diagnosis, which often relies on histopathologic interpretation of small tissue samples from oral lesions. While confident diagnosis of small oral biopsies can be challenging, an understanding of oral and maxillofacial disease and consistent clinicopathologic correlation can help pathologists recognize inflammatory confounders and overcome common errors in specimen management, including insufficient sample size and non-representative biopsy samples.

Clinicopathological characteristics of high-altitude polycythemia-related kidney disease in Tibetan inhabitants.

High-altitude polycythemia (HAPC) is a clinical syndrome that occurs in native inhabitants or long-term residents living at altitude. The kidney is one of the most affected organs. However, the clinical and kidney histopathological profiles of HAPC-related kidney disease have rarely been reported. Here, we report kidney biopsy-based clinicopathological study on this disease. HAPC was defined as excessive erythrocytosis [females, hemoglobin 190 g/L or more; males, 210 g/L or more] in patients living above an altitude of 2500 m for more than ten years. A total of 416 Tibetan patients underwent kidney biopsy between January 1, 2016, and November 31, 2020. Of these patients 17 met the diagnostic criteria for HAPC-related kidney disease. Clinically, these patients had a median urinary protein level of 2.5 g/24-hour (range 1.81-6.85). Twelve patients had hyperuricemia, nine had hypertension, and three had kidney insufficiency. On histopathology, glomerular hypertrophy, glomerular basement membrane thickening, podocyte foot process effacement, segmental glomerulosclerosis and global glomerulosclerosis were the main features. Extraglomerular arterial/arteriolar lesions were common, presenting as intimal fibrosis, hyalinosis and endothelial cell swelling/subintimal edema. Expansion of the arterial/arteriolar medial wall area characterized by smooth muscle cell proliferation was clearly observed, potentially indicating vascular remodeling. Hypoxia-inducible factor 2α was expressed in the kidney tissues of these patients. Thus, the pathological changes of HAPC-related kidney disease encompassed both glomerular and extraglomerular vascular lesions, suggesting a key role of both chronic hypoxia itself and secondary hemodynamic changes in the pathogenesis of this disease.

Clinicopathologic analysis of trichoblastoma and comparison with nodular basal cell carcinoma.

BACKGROUND: Trichoblastoma (TB) is an uncommon benign follicular tumour for which clinical data is limited since most reports originate from pathology studies. OBJECTIVE: To describe the clinical aspects of TB. METHODS: This is an ancillary study of a prospective multicentre cohort of 2710 clinically suspected basal cell carcinoma (BCC), including 935 nodular BCCs. Sixty-two cases were TB: they were analysed and compared to 935 nodular BCCs. RESULTS: TB mostly occurred in females (61% vs. 43% for BCC, P<0.01) of mean age 63 years. They were located on the head and neck, mainly on the nose and forehead, in 87% of cases. The mean size was 8.1mm, 77% were<10mm (55% of BCCs, P<0.001), 8% were ulcerated (vs. 21% of BCCs, P<0.02), and 47% persisted for more than 1 year (34% of BCCs, P<0.05). Most cases had a clinical presentation similar to nodular BCC, except for 5 small, flat, white papules and 1 anfractuous plaque. LIMITATIONS: Cases originated from a series of tumours clinically suspected as BCCs. DISCUSSION: Some 2.6% of tumours clinically diagnosed as BCC are in fact TB. TB occurs on the head, are more frequent in women, and are smaller and of longer duration than BCC. In most cases, clinical diagnosis on clinical grounds is difficult.

Histopathologic vasculitis from the periulcer edge: A retrospective cohort study.

BACKGROUND: Histopathologic vasculitis is often reported in periulcer specimens, but the frequency and clinical significance of this finding have not been evaluated. OBJECTIVE: We evaluated the sensitivity, specificity, negative predictive value, and positive predictive value of histopathologic vasculitis from the periulcer edge for detecting ulcers due to cutaneous vasculitis. METHODS: We performed a retrospective chart review of patients with leg ulcers at a tertiary hospital between 2009 and 2016. Histopathologic slides were evaluated by 2 dermatopathologists who were blinded to the etiology of ulcer. Focal vasculitis was defined as involvement of fewer than 3 vessels. RESULTS: Vasculitis at the periulcer edge was seen in 51.6% of the specimens (32 of 62). Of the specimens with histopathologic vasculitis, focal vasculitis was seen in the majority of specimens (71.9% [23 of 32]), whereas diffuse vasculitis was observed in 28.1% (9 of 32). Periulcer vasculitis yielded a high sensitivity (100% [95% confidence interval, 29%-100%]). Furthermore, the specificity was low (50.9% [95% confidence interval, 38.1%-63.6%]) for detecting vasculitis-induced ulcers. LIMITATIONS: Small number of vasculitis-induced ulcers. CONCLUSION: Focal vasculitis from the periulcer edge is a nonspecific finding and provides little diagnostic value in determining the etiology of lower leg ulcers. Emphasis should be placed on the combination of clinical history and examination, histology, and laboratory findings when diagnosing ulcers.

Epidermotropic presentation by splenic B-cell lymphoma: The importance of clinical-pathologic correlation.

There are exceedingly rare reports of patients with epidermotropic B-cell lymphomas. A subset presented with intermittent, variably pruritic papular eruptions and involvement of their spleens, peripheral blood and bone marrow at the time of diagnosis. Furthermore, some experienced an indolent course despite dissemination of their lymphomas. We report a 66-year-old woman with a 12-year history of intermittent eruptions of non-pruritic, salmon-colored papules on her torso and proximal extremities that occurred in winter and resolved with outdoor activity in spring. Skin biopsy revealed an epidermotropic B-cell lymphoma with a non-specific B-cell phenotype and heavy chain class switching with IgG expression. On workup, our patient exhibited mild splenomegaly and low-level involvement of her peripheral blood and bone marrow by a kappa-restricted B-cell population. A splenic B-cell lymphoma was diagnosed. Considering her longstanding history and absences of cytopenias, our patient has been followed without splenectomy or systemic therapy. Furthermore, the papules have responded dramatically to narrowband UVB. Our case and a review of similar rare reports aim to raise awareness among dermatopathologists and dermatologists of a clinically distinct and indolent subset of epidermotropic splenic lymphomas with characteristic clinical and histologic findings.

Permanent alopecia in patients with breast cancer after taxane chemotherapy and adjuvant hormonal therapy: Clinicopathologic findings in a cohort of 10 patients.

BACKGROUND: Anagen effluvium with reversible scalp alopecia is a known side effect of chemotherapy. However, there are an increasing number of reports in the literature documenting permanent alopecia in patients treated with taxanes. OBJECTIVE: We sought to describe the clinicopathologic features in breast cancer patients who underwent treatment with taxanes and adjuvant hormonal chemotherapy. METHODS: We reviewed the clinical and histopathologic information of a cohort of 10 patients treated with taxanes and adjuvant hormonal chemotherapy. RESULTS: We have observed 3 types of clinical patterns of alopecia (types A, B, and C), and have validated the histopathologic features showing alopecia areata-like and female pattern hair loss. LIMITATIONS: The study was based on a small sample size and retrospective retrieval of clinical information and histopathologic review of posttreatment slides. CONCLUSIONS: We hypothesize a clinicopathologic model of hair follicle cycle disruption in response to the chemoinflammatory and hormonal insults to the hair follicles resulting in permanent alopecia. Clinicopathologic correlation is paramount to the understanding of the morphobiologic pathways in chemotherapy-induced alopecia caused by taxanes and adjuvant hormonal treatment.

Prior knowledge of the clinical picture does not introduce bias in the histopathologic diagnosis of melanocytic skin lesions.

A common debate among dermatopathologists is that prior knowledge of the clinical picture of melanocytic skin neoplasms may introduce a potential bias in the histopathologic examination. Histologic slides from 99 melanocytic skin neoplasms were circulated among 10 clinical dermatologists, all of them formally trained and board-certified dermatopathologists: 5 dermatopathologists had clinical images available after a 'blind' examination (Group 1); the other 5 had clinical images available before microscopic examination (Group 2). Data from the two groups were compared regarding 'consensus' (a diagnosis in agreement by ≥4 dermatopathologists/group), chance-corrected interobserver agreement (Fleiss' k) and level of diagnostic confidence (LDC: a 1-5 arbitrary scale indicating 'increasing reliability' of any given diagnosis). Compared with Group 1 dermatopathologists, Group 2 achieved a lower number of consensus (84 vs. 90) but a higher k value (0.74 vs. 0.69) and a greater mean LDC value (4.57 vs. 4.32). The same consensus was achieved by the two groups in 81/99 cases. Spitzoid neoplasms were most frequently controversial for both groups. The histopathologic interpretation of melanocytic neoplasms seems to be not biased by the knowledge of the clinical picture before histopathologic examination.

Defining early mycosis fungoides: validation of a diagnostic algorithm proposed by the International Society for Cutaneous Lymphomas.

BACKGROUND: Mycosis fungoides (MF) is the most common subtype of cutaneous T-cell lymphoma and is often difficult to diagnose. Early-stage disease is particularly challenging and requires clinical and histopathologic correlation to make an accurate diagnosis. In order to facilitate the diagnosis of early MF, an algorithm has been proposed by the International Society for Cutaneous Lymphomas (ISCL) whereby clinical and histopathologic characteristics as well as immunohistochemistry and T-cell receptor gene rearrangement studies may be applied to suspected cases of MF. The diagnostic utility of this algorithm has not yet been validated. We sought to determine the validity of the proposed algorithm via an investigator-blinded, retrospective, case-control study. METHODS: A total of 34 cases were randomly selected from the database of a clinic for cutaneous T-cell lymphomas and included patients with MF and patients with clinicopathologic mimics. The proposed diagnostic algorithm was systematically applied to the entire cohort. Each case was assigned a composite score based on the parameters in the proposed algorithm. RESULTS: Among the 24 cases of MF, 21 cases achieved four or more points through application of the algorithm. Among the 10 cases of MF mimics, only four achieved four or more points. This difference was significant (Fisher's exact test, p = 0.009). The sensitivity of the 4-point threshold for a diagnosis of MF was 87.5% and the specificity was 60%. CONCLUSIONS: The diagnostic algorithm proposed by the ISCL is a statistically valid method for defining cases of early MF and distinguishing these cases from other benign dermatoses. However, the clinical utility of the algorithm may be limited by its low specificity. Further refinement of the algorithm may improve its accuracy.

Influence of clinical and pathologic features on the pathologist's diagnosis of mycosis fungoides: a pilot study.

Although clinicopathologic correlation is critical in the diagnosis of early mycosis fungoides (MF), how clinical information directly affects the pathologist's interpretation is unknown. This pilot study aimed to assess the influence of provided clinical information and specific histopathologic features on the histopathologic diagnosis of MF vs. its inflammatory simulants. A computerized survey recorded diagnostic impressions by 24 dermatopathologists of 30 hematoxylin-eosin stained images, including 15 MF images and 15 dermatitis images. Images were accompanied by concordant clinical descriptions (33%), no clinical information (33%) or discordant clinical descriptions (33%). Percentage of correctly classified MF histopathologic images for the three scenarios of concordant clinical information, no clinical information or discordant clinical information were 32% (kappa 0.19), 56% (kappa 0.12) and 16% (kappa 0.33), respectively. The percentage of correctly classified slides presented with no clinical information was different from the other two groups (p < 0.0001). Pautrier collections were most associated with correct classification. Clinical information may play a significant role in the histopathologic diagnosis of MF, although there may be some value in initial blinded histopathologic interpretation. Specific histopathologic features differ in relative importance in the diagnosis of MF.

Cytopathology and clinicopathological correlation of renal neuroendocrine neoplasms.

INTRODUCTION: There is a lack of documentation regarding cytopathology of renal neuroendocrine neoplasms (NENs) due to their rarity. MATERIALS AND METHODS: Five cytology cases were gathered from 3 institutes. RESULTS: Cohort consisted of 4 females and 1 male. Fine needle aspiration biopsy and touch preparation slides of core needle biopsy revealed cellular samples, composed of round, plasmacytoid, or columnar cells. Tumor cells were present in nested, acinar, 3D cluster, and individual cell patterns. Tumor cells in 3 cases exhibited uniformly round to oval small nuclei with inconspicuous nucleoli, finely granular chromatin, and smooth nuclear membranes, whereas 2 other cases showed pleomorphic nuclei with conspicuous nucleoli, nuclear molding, and irregular nuclear membranes. Tumor cells displayed pale or granular cytoplasm, with 1 case showing small vacuoles. Examination of cores and cell blocks demonstrated tumor cells in sheets, nests, or acini. All tumor cells were positive for neuroendocrine immunomarkers. Based on mitotic count, Ki-67 index and morphology, 3 tumors were graded as well-differentiated neuroendocrine tumor (WDNET) (1 grade [G] 3, 1 G2, 1 G1) and 2 as large cell neuroendocrine carcinoma. Deletion of 7q, 10q, and 19q was detected in WDNETs. Two patients with large cell neuroendocrine carcinoma and 1 with WDNET G3 underwent chemotherapy due to aggressiveness, whereas nephrectomy was performed for patients with WDNET G1 and 2 without metastasis. CONCLUSIONS: Cytopathological characteristics of renal NENs closely resemble those affecting other organs. Despite its rarity, renal NENs should be kept in mind when confronted with morphological resemblances to NENs, to prevent misdiagnosis and inappropriate therapeutic interventions.

Cutaneous Reactions after COVID-19 Vaccines: Analysis of the Clinical and Histopathological Spectrum-Case Series and Review of the Literature.

(1) Background: Various cutaneous adverse drug reactions (ADRs) are observed with the implementation of mRNA COVID-19 vaccines. To gain insight into the clinicopathologic features, we analyzed the correlation of histological and clinical data in 48 patients with these ADRs. (2) Methods: Single-center retrospective study in patients with ADRs after mRNA COVID-19 vaccination (mRNA-1273 and BNT162b2 vaccines). (3) Results: Distant generalized ADRs prevailed (91%), often appearing clinically as spongiotic dermatitis or maculopapular exanthema. Histopathological analysis revealed spongiotic changes (46%) and dermal superficial perivascular predominantly lymphocytic infiltrates (17%). Eosinophils were found in 66% of biopsies, neutrophils in 29%, and plasma cells only in 8% of biopsies. Most ADRs occurred after the second vaccine dose (44%). Histologically spongiotic changes were associated with clinical features of spongiotic dermatitis in only 50% of patients and maculopapular exanthema in the remaining patients. ADRs represented an aggravation of preexisting skin disease in 23% of patients. ADRs regressed within 28 days or less in 53% of patients and persisted beyond a month in the remaining patients. (4) Conclusions: Our study demonstrates a diverse spectrum of generalized ADRs, revealing correlations between histology and clinical features but also instances of divergence. Interestingly, in about half of our patients, ADRs were self-limited, whereas ADRs extended beyond a month in the other half.

Clinicopathologic correlation of dermatologic diseases in patients with darker pigmentation.

OBJECTIVES: Cutaneous diseases that disproportionately affect patients with darker pigmentation and their histologic features are historically understudied and undertreated. This review article aims to highlight the key clinical features, histopathology, and diagnostic pearls of several cutaneous diseases that commonly present in patients with darker pigmentation. METHODS: A literature search was conducted, and a list of cutaneous diseases that frequently affect patients with darker pigmentation was compiled. A group of experts expounded upon those that were most common or misdiagnosed according to scientific evidence and clinical practice. RESULTS: The diseases were divided into hypopigmented disorders, hyperpigmented disorders, scarring disorders, and alopecic disorders. Within each category, the etiology, clinical features, histopathology, and key histologic differential diagnoses are described and discussed. CONCLUSIONS: As many clinicians are taught that there are no effective treatment options or that these diseases are considered "cosmetic" in nature, patients often do not get a thorough medical workup or skin biopsy. This article aims to decrease the knowledge gap and serve as a resource for anyone involved in the care of patients with these cutaneous conditions.

Exploring the prognosis value, immune correlation, and drug responsiveness prediction of homeobox C6 (HOXC6) in lung adenocarcinoma.

BACKGROUNDS: Homeobox C6 (HOXC6) is a gene that encodes for a transcription factor involved in various cellular processes, including development and differentiation, and regulates cancer progression. However, the carcinogenesis and effect of HOXC6 in lung adenocarcinoma (LUAD) still need further investigation. METHODS: The differential HOXC6 expression levels at the mRNA and protein level were explored in multiple public datasets, including The Cancer Genome Atlas (TCGA) and Human Protein Atlas (HPA) dataset. Gene Expression Omnibus (GSE31210), International Cancer Genome Consortium (ICGC) datasets and the LUAD sample from Affiliated Hospital of Guangxi Medical University. We also investigated the relation between HOXC6 expression and clinicopathologic indexes. Furthermore, the correlation of immune infiltration, drug responsiveness and HOXC6 were explored. RESULTS: The upregulated HOXC6 expressions at mRNA and protein levels were found in LUAD tissues compared to the normal lung tissues. Besides, the relatively shorter overall survival time, worse T and N stages, and lower immune scores were found in the high-expression HOXC6 subgroup. Notably, T cells regulatory (Tregs), Macrophages M0, and Plasma cells had the higher infiltration levels in the high-HOXC6 expression subgroup, while NK cells activated, Monocytes, Dendritic cells resting, and Mast cells resting had the lower infiltration levels. In drug sensitivity analysis, we revealed that LUAD patients with high-HOXC6 expression may be more susceptible to Camptothecin, Cytarabine, Docetaxel, Elesclomol, Rapamycin, Sorafinib, Temsirolimus, and Vorinostat. CONCLUSIONS: Taken together, there is a great potential for HOXC6 to become a prognosis biomarker and contribute to develop treatment strategies for LUAD patients. Further mechanism exploration and drug development for HOXC6 are needed.

Strategies for Diagnosing and Treating Disseminated Methicillin-Sensitive Staphylococcus aureus Infections: Insights From a Pustular Eruption.

A 63-year-old immunocompromised male with a history of renal transplant and stage III large B-cell non-Hodgkin lymphoma undergoing rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) therapy presented with fever and a disseminated pustular eruption. Initial laboratory values indicated septicemia. Differential diagnoses included Sweet's syndrome, septic emboli, and leukocytoclastic vasculitis. Punch biopsies and bacterial cultures confirmed disseminated methicillin-sensitive Staphylococcus aureus (MSSA) infection. Histopathology revealed intraepidermal vesiculopustules and bacterial cocci colonies in the superficial dermis, suggesting hematogenous spread. The patient's indwelling venous access port was identified as the infection source and removed. Treatment included antibiotics such as cefepime, vancomycin, fluconazole, and acyclovir, as well as filgrastim for neutropenia. Following port removal and a four-week course of ceftriaxone, the patient's condition improved. This case highlights the importance of clinicopathologic correlation in diagnosing and managing disseminated staphylococcal infections in immunocompromised patients. The rare presentation of vesiculopustular eruptions secondary to MSSA emphasizes the need for prompt identification and treatment to prevent severe complications. This report contributes to the limited literature on disseminated staphylococcal infections presenting as vesiculopustular eruptions in immunocompromised individuals.

Clinicopathologic analysis of a case of small cell lung carcinoma metastatic to the retina.

Purpose: Tumor metastases to the retina are a relatively rare occurrence. We report a unique case of retinal metastasis of a systemic malignancy with clinical and histopathologic correlations. Observations: A 62-year-old female with a history of stage IV small cell carcinoma of the lung (SCC, status post chemotherapy and maintenance immunotherapy) presented with hand motions vision and vitreous hemorrhage, status post prior vitrectomy and biopsy that was non-diagnostic. She was found to have unilateral retinal metastatic tumor and underwent a repeat vitrector-assisted biopsy which confirmed the diagnosis. The eye became blind and painful due to recurrent non-clearing vitreous hemorrhage and ghost cell glaucoma and was enucleated. Detailed histopathologic analysis of the globe confirmed small cell carcinoma metastatic to the retina and vitreous cavity and sparing the choroid. Conclusions and importance: This case demonstrates the importance of maintaining a high index of suspicion for metastasis in patients with a known history of malignancy who present with new vitreoretinal lesions.

Cytomorphology, immunoprofile, and clinicopathologic correlation of metastatic prostatic carcinoma.

It may be challenging to diagnose metastatic prostatic carcinoma (PC). This study focused on clinicopathologic correlation, and pitfalls of cytomorphology and immunostains of metastatic PCs. A total of 146 metastatic PCs including 134 (92%) PC without neuroendocrine differentiation-prostatic adenocarcinoma (PAC) and 12 (8%) with neuroendocrine differentiation (PC-NED) were retrieved. Triplicate tissue microarrays (TMA) of 54 surgically excised PCs were constructed for immunostains. Most cases showed Gleason 4 or 5 patterns. Nine percent of cases did not have a prior history of PC and 7% had 2 or more primary malignancies. PAC metastasized more commonly to lymph nodes (49%), and PC-NED metastasized more commonly to liver (58%). Cytologically, metastatic PCs show acini, cribriform, nest, and solid clusters. Most PACs showed conspicuous or prominent nucleoli. PC-NEDs showed typical cytologic features of low-grade or high-grade neuroendocrine neoplasm, or small cell carcinoma features. PACs could be immunoreactive to CDX2 (25%), CK20 (11%), NKX3.1 (99%), PSA (88%), PSAP (78%), and PSMA (92%). PC-NEDs were immunoreactive to neuroendocrine immunomarkers (CD56 [100%], chromogranin [67%], and synaptophysin [100%]) and p63 (25%), and lost expression of prostate-specific markers (NKX3.1, PSA, PSAP, and PSMA). Both PACs and PC-NEDs might be immunoreactive to CK7 (18% versus 33%), GATA3 (4% versus 0%), PAX8 (2% versus 50%, P < .05), and TTF1 (3% versus 57%, P < .05). It is critical to recognize these cytologic features and abbreviation of immunomarkers of metastatic PCs to avoid misinterpretation as metastatic carcinoma from nonprostate organs and inappropriate treatment. In addition, NED may be seen after hormone and chemoradiation treatment.

The Biological Synthesis and the Function of Mucin 2 in Pseudomyxoma Peritonei.

Excessive mucus secretion is the most prominent feature of pseudomyxoma peritonei (PMP), which often leads to significant increase in abdominal circumference, intractable abdominal pain, progressive intestinal obstruction, abdominal organ adhesions, and cachexia. Excessive mucus secretion is also the main cause of death. Cytoreductive surgery (CRS) combined with hyperthermic intraperitoneal chemotherapy (HIPEC) is the recommended treatment for PMP. However, recurrence is frequently observed even after CRS and HIPEC, presenting similar clinical manifestations. Mucin 2 (MUC2) is the main type of mucin in PMP and plays a key role in the progressive sclerosis of mucus. To comprehensively demonstrate the biosynthetic process and molecular features of MUC2 and to provide new directions for the development of PMP mucolytic strategies, this review systematically summarizes the molecular biology of MUC2, including MUC2 gene structure, transcription, translation, post-translational modification, tertiary structure, and factors regulating mucus viscoelasticity. The results show that MUC2 is a highly glycosylated protein, with glycan accounts for 80% to 90% of the dry weight. The assembly pattern of MUC2 is highly complicated, presenting a bead-like filament. Salt concentration, pH, mucin concentration and trefoil factor family may contribute to the increase in mucus viscoelasticity and sclerosis, which could be used to develop drugs to soften or even dissolve mucus in the future.