Application of INSM1 in Diagnosis and Grading of Laryngeal Neuroendocrine Carcinoma

Insulinoma-associated protein-1 (INSM-1) is a useful diagnostic marker for the evaluation of primary thymic neuroendocrine neoplasms: an immunohistochemical study of 27 cases

Insulinoma-associated protein 1 (INSM1) immunohistochemistry has been established as a sensitive and reliable immunohistochemical marker for detecting neuroendocrine differentiation in tumors across various organ systems. However, this marker has not been adequately investigated in primary thymic neuroendocrine tumors. We have studied a series of 27 cases of primary neuroendocrine carcinomas of the thymus, including 3 typical carcinoids, 18 atypical carcinoids, 4 large cell neuroendocrine carcinomas, and 2 small cell carcinomas. Immunostaining on whole tissue sections for INSM-1 was evaluated. Results of immunostaining for chromogranin and synaptophysin were also evaluated. 26/27 tumors (96%) demonstrated nuclear positivity for INSM1. 18 tumors (67%) showed strong and diffuse nuclear staining (3 +), 3 tumors (11%) moderate (2 +) nuclear staining, and 5 tumors (19%) showed weak (1 +) nuclear staining. The average percentage of tumor cells positive for INSM1 was 76%. Only one tumor, a small cell carcinoma, was negative. All tumors were positive for synaptophysin, and 26/27 (96%) were positive for chromogranin A. This study confirms that INSM1 immunohistochemistry is a sensitive marker of neuroendocrine differentiation in primary thymic neuroendocrine neoplasms and demonstrates similar performance characteristics compared to other organ systems. The nuclear staining with this marker offers the advantage of eliminating some of the ambiguity in the interpretation sometimes encountered with other markers. An added advantage is the consistent staining across the entire spectrum of neuroendocrine tumors of this organ.

Insulinoma-Associated Protein-1 Expression in Lymphoepithelial Carcinoma of the Thymus: A Potential Pitfall for Diagnosis With Neuroendocrine Carcinomas of the Thymus

CONTEXT.—

Insulinoma-associated protein-1 (INSM1) is a recently developed immunohistochemical marker claimed to be highly specific and sensitive for the diagnosis of neuroendocrine malignancies. Recent studies, however, have demonstrated that this marker can also be expressed in non-neuroendocrine neoplasms including squamous cell carcinoma of the thymus.

OBJECTIVE.—

To examine INSM1 expression in lymphoepithelial thymic carcinomas.

DESIGN.—

Thirty-four cases of lymphoepithelial carcinoma of the thymus were examined by immunohistochemistry or in situ hybridization for INSM1, synaptophysin, chromogranin, CD5, CD117, Epstein-Barr virus-encoded small ribonucleic acid (EBER), and Ki-67. Basic clinical information was abstracted from the medical record.

RESULTS.—

The patients were 14 women and 20 men, aged 20 to 85 years. The tumors arose in the anterior mediastinum without any previous history or evidence of malignancy at other sites. Immunohistochemical staining showed moderate to strong positivity of the tumor cells for INSM1 in 65% of cases (22 of 34), focal weak positivity in 20% (7 of 34), and negative staining in 5 cases. Chromogranin staining was focally and weakly positive in 1 case, and synaptophysin showed only focal weak positivity in scattered tumor cells in 12 cases. No significant correlation could be identified between the pattern and intensity of staining for INSM1 and staining for CD5, CD117, and Ki-67.

CONCLUSIONS.—

INSM1 positivity in lymphoepithelial carcinoma of the thymus may represent a pitfall for diagnosis, particularly in small biopsy samples. Awareness of this finding may be of importance to avoid misdiagnosis of neuroendocrine malignancy.

Giant laryngeal neuroendocrine neoplasm causing airway obstruction: A case report and literature review

RATIONALE

Laryngeal neuroendocrine neoplasm (NEN) is a rare and heterogeneous disease that originates from neuroendocrine cells. It mainly occurs in middle-aged and elderly men. Due to the lack of specific clinical and imaging manifestations, diagnosis and treatment of the disease pose a challenge. Therefore, a consensus on the diagnosis and treatment of the disease is necessary. By discussing this case, we will be able to gain further insight into laryngeal NEN and will be able to provide some recommendations for the future management of this rare disease.

PATIENT CONCERNS

A 67-year-old man was admitted to our department with a history of sore throat and dyspnea. After admission, the patient experienced acute airway obstruction and experienced an emergency bedside tracheotomy.

DIAGNOSES

Flexible fiberoptic laryngoscopy and enhanced CT showed a cauliflower-like mass in the left supraglottic region and obstructed most of the laryngeal cavity. We biopsied the mass, and the pathology showed a poorly differentiated adenocarcinoma.

INTERVENTIONS

A horizontal hemilaryngectomy and left neck dissection were performed. At 4 weeks after the operation, the patient underwent chemotherapy and radical radiotherapy.

OUTCOMES

After a 1-year postoperative follow-up, the patient recovered well and showed no signs of recurrence.

LESSONS

Laryngeal neuroendocrine neoplasm is very rare, early diagnosis remains difficult. Radical surgery combined with postoperative chemoradiotherapy is currently the most appropriate treatment.

Comparison of INSM1 immunostaining with established neuroendocrine markers synaptophysin and chromogranin A in over 14,000 neuroendocrine and non-neuroendocrine tumors

INSM1 is a transcription factor protein which is increasingly used as an immunohistochemical marker for neuroendocrine differentiation. To determine the prevalence of INSM1 expression in tumors and its expression pattern in normal tissues, tissue microarrays containing 14,908 samples from 117 different tumor types/subtypes as well as 76 different normal tissues were analyzed by immunohistochemistry. INSM1 was positive in 89.2% of 471 neuroendocrine neoplasms (NEN) and in 3.5% of 11,815 non-neuroendocrine neoplasms that were successfully analyzed. At least an occasional weak INSM1 positivity was observed in 59 different non-neuroendocrine tumor entities, of which 15 entities contained at least one case with strong INSM1 staining. A comparison with synaptophysin and chromogranin A staining revealed that in NEN, synaptophysin showed the highest sensitivity (93.3%), followed by INSM1 (89.2%) and chromogranin A (87.5%). In neuroendocrine carcinomas (NEC), sensitivity was highest for INSM1 (88.0%), followed by synaptophysin (86.5%) and chromogranin A (66.4%). If INSM1 was used as an additional marker, the sensitivity for detecting neuroendocrine differentiation in NEN increased from 96.6% (synaptophysin and chromogranin A) to 97.2% (synaptophysin, chromogranin A and INSM1). Our study shows that INSM1 is a useful additional marker for neuroendocrine differentiation with high sensitivity, particularly in NEC.

Osamura R, Shiomi T, Matsuno A. Analysis of Insulinoma-Associated Protein 1 Expression in Pituitary Neuroendocrine Tumors

Insulinoma-associated protein 1 (INSM1) is a representative diagnostic marker of neuroendocrine neoplasms (NENs); however, it has not yet been used to diagnose pituitary neuroendocrine tumors (PitNETs), according to the 2022 World Health Organization (WHO) classification of pituitary tumors. This study aimed to examine the expression of INSM1 using immunohistochemistry, in the various cell lineages of PitNET classified by hormone secretion and transcription factor expression. INSM1 expression in PitNETs (different subtypes) and normal pituitary tissues was immunohistochemically assessed. The results were interpreted as scores of 0 (negative), 1 (focally positive), or 2 (frankly positive), depending on the proportion of cell staining. Twenty-eight of 35 PitNET cases (80%) showed INSM1 positivity in their nuclei. The staining in each histological subtype of PitNETs was as follows: somatotroph tumors, score 0 = 3/5, score 1 = 1/5, score 2 = 1/5; lactotroph tumors, score 0 = 2/5, score 1 = 1/5, score 2 = 2/5; thyrotroph tumors, score 2 = 5/5; corticotroph tumors: score 1 = 1/9, score 2 = 8/9; gonadotroph tumors, score 0 = 2/10, score 1 = 0/10, score 2 = 8/10; and unclassifiable tumor, score 1 = 1/1. INSM1 expression in most PitNETs was obtained, similar to that in the normal pituitary gland; thus, INSM1 may maintain the characteristics of anterior pituitary cells and pituitary tumors.

Atypical Carcinoid of the Larynx: A Case Report

Neuroendocrine carcinomas are a spectrum of rare and highly heterogeneous malignant tumors. Neuroendocrine carcinomas mainly arise from neuroendocrine cells scattered throughout the body. They mainly occur in the lung and gastrointestinal tract. Atypical carcinoid of the larynx is a rare type of neuroendocrine carcinoma, which is easily misdiagnosed as hemangioma in appearance. We mainly feature the disease to you through the diagnosis and treatment of a case of atypical carcinoid of the larynx.

Clinical Diagnosis and Treatment of Primary Laryngeal Neuroendocrine Carcinoma

OBJECTIVE

This study aims to investigate the clinical diagnosis and treatment characteristics of primary laryngeal neuroendocrine carcinoma.

PATIENTS AND METHODS

A retrospective analysis was performed for the data of 6 patients with primary laryngeal neuroendocrine carcinoma admitted to the Department of Otorhinolaryngology of Dalian Central Hospital from September 2015 to January 2022, all of whom were male patients. And laryngoscopy showed that 4 had a similar appearance to hemangioma, 1 had nodular hyperplasia, and 1 was papilloma-like. The site of onset was located on the laryngeal surface of the epiglottis in 3 cases, situated in the aryepiglottic fold in 2 cases, and the posterior ventricular zone in 1 case. Five patients underwent surgery, including 4 by transoral endoscopic cryogenic plasma radiofrequency mass resection; one underwent a cervical lymph node dissection and supraglottic horizontal hemilaryngectomy. The remaining 1 case was treated in another hospital after the pathological diagnosis was confirmed by biopsy. All patients had no cervical lymph node metastases and were not supplemented with chemoradiotherapy.

RESULTS

The postoperative pathological diagnosis of all 5 patients was neuroendocrine carcinoma. No cancer cells were seen at the margins and base. One patient was lost to follow-up after treatment in another hospitals and the rest were followed up for 6 months to 6 years. One patient had removed laryngeal tumor and epiglottis by a low-temperature plasma radiofrequency ablation, recurrence 1 year after surgery, and no recurrence for 5 years after supraglottic horizontal hemilaryngectomy combined with prophylactic cervical lymph node dissection, no recurrence for the other 4 patients after 6 months to 4 years of follow-up.

CONCLUSION

The common sites of laryngeal neuroendocrine carcinoma are the laryngeal surface of the epiglottis and the aryepiglottic fold. The appearance of the tumor is mainly similar to that of hemangioma. Moreover, a common pathological classification is atypical carcinoid tumors, where early detection and surgical treatment can achieve a good therapeutic effect.

The Complex Histopathological and Immunohistochemical Spectrum of Neuroendocrine Tumors-An Overview of the Latest Classifications

Neuroendocrine neoplasms (NENs) originate from the neuroendocrine cell system, which may either take the shape of organoid cell aggregations or be composed of dispersed cells across various organs. Therefore, these tumors are heterogenous regarding the site of origin, functional status, degree of aggressiveness, and prognosis. When treating patients with neuroendocrine tumors, one of the most significant challenges for physicians is determining the correct tumor grade and thus classifying patients into risk categories. Over the years, the classification of these tumors has changed significantly, often causing confusion due to clinical, molecular, and immunohistochemical variability. This review aims to outline the latest NENs classifications regardless of their site of origin. Thus, an overview of the key histopathological and immunohistochemical characteristics of NENs could pave the way to validate possible predictive and prognostic markers and also guide the therapeutic conduct.

Insulinoma-Associated Protein 1 (INSM1): Diagnostic, Prognostic, and Therapeutic Use in Small Cell Lung Cancer

Small cell lung carcinoma (SCLC) is an aggressive and difficult to treat cancer. Although immunohistochemistry is not mandatory for a SCLC diagnosis, it might be required, especially in small samples. Insulinoma-associated protein 1 (INSM1) is expressed in endocrine and nervous tissues during embryogenesis, generally absent in adults and re-expressed in SCLC and other neuroendocrine neoplasms. Its high specificity propelled its use as diagnostic biomarker and an attractive therapeutic target. Herein, we aim to provide a systematic and critical review on the use of INSM1 for diagnosis, prognostication and the treatment of SCLC. An extensive bibliographic search was conducted in PubMed® focusing on articles published since 2015. According to the literature, INSM1 is a highly sensitive (75–100%) and specific (82–100%) neuroendocrine immunohistochemical marker for SCLC diagnosis. It can be used in histological and cytological samples. Although advantageous, its standalone use is currently not recommended. Studies correlating INSM1 expression and prognosis have disclosed contrasting results, although the expression seemed to entail a worse survival. Targeting INSM1 effectively suppressed SCLC growth either as a suicide gene therapy regulator or as an indirect target of molecular-targeted therapy. INSM1 represents a valuable biomarker for a SCLC diagnosis that additionally offers vast opportunities for the development of new prognostic and therapeutic strategies.