Polypoid laryngeal inflammatory myofibroblastic tumors: misleading lesions: description of six cases showing ALK overexpression

TIMP3::ALK fusions characterize a distinctive myxoid fibroblastic tumor of the vocal cords: a report of 7 cases

We report 7 cases of an indolent, variably myxoid tumor of the vocal cords, characterized by overt cellular atypia with large cells containing intranuclear and intracytoplasmic vacuoles, delicate curvilinear vessels, and sparse inflammatory infiltrate. Six patients were male, aged 15 to 65 years, and 1 patient was a 54-year-old female. All tumors were located in the superficial portion of the vocal cord. One patient suffered a recurrence that was completely resected; all patients with available follow-up data currently have no evidence of disease. The tumors contained alternating areas with myxoid stroma and more compacted regions with tumor cells organized in short fascicles, interwoven with delicate curvilinear vasculature. Overt cellular atypia with large cells containing intranuclear and intracytoplasmic vacuoles or resembling ganglion cells was present in all cases but mitoses and necrosis were absent. ALK immunostaining was positive in all cases, while most tumors were negative for smooth muscle actin. Targeted RNA-sequencing revealed an identical TIMP3::ALK fusion with exon 1 of TIMP3 gene being fused with exon 12 of ALK gene in all analyzable cases. For various reasons discussed, it remains unclear whether this tumor represents a mere subtype of IMT or a separate entity. Nevertheless, it is a morphologically distinct and diagnostically challenging lesion that needs to be recognized by surgical pathologists in order to prevent overdiagnosis in this clinically very delicate area.

Well-differentiated Spindle Cell Liposarcoma of the Larynx: A Rare Case Report and Review of Literature

BACKGROUND

Liposarcoma of the larynx is a rare entity. Well-differentiated spindle cell liposarcoma of the larynx has not been yet reported in the literature.

CASE REPORT

We report the first case of well-differentiated spindle cell liposarcoma of the larynx on a 59-year-old male who presented with change of voice and phlegmy cough for several months. Laryngoscopy revealed a mucosal covered pedunculated mass on the supraglottis. Computerized tomography (CT) scan showed a low-attenuation mass causing moderate narrowing of the airway. The lesion was excised. Grossly, a 4.2 cm ovoid, solid and soft mass with homogeneously white-gray and rubbery cut surface was identified. Microscopic examination revealed a well-demarcated neoplasm composed of predominantly atypical and pleomorphic spindle cells distributed in collagenous stroma, with admixed adipocytes showing variation in cell size and rare lipoblasts. Immunohistochemical stains showed that the spindle cells were positive for MDM2, CDK4, and CD34. Overall, the histology and immunoprofile are consistent with a well-differentiated liposarcoma, spindle cell type. Due to the positive resection margin, the patient subsequently received endoscopic local re-excision with a carbon dioxide laser. He did well at 4 months after primary excision.

CONCLUSION

This case illustrates that while well-differentiated spindle cell liposarcoma rarely occurs in the larynx, it should be considered in the differential diagnosis of patients with laryngeal lesions. A panel of immunohistochemistry markers including MDM2, CDK4 and CD34 is helpful to render accurate diagnosis. Wide excision with long-term follow-up is necessary for this rare variant of liposarcoma.

Epstein-Barr Virus-Associated Smooth Muscle Tumors of Larynx: A Clinicopathologic Study and Comprehensive Literature Review of 12 Cases

Laryngeal mesenchymal neoplasms are rare, with smooth muscle tumors comprising a small subset. Specifically, Epstein-Barr virus (EBV)-associated smooth muscle tumors are exceptionally rare, lacking a comprehensive evaluation of their clinical and histologic features. Two patients (a 59 year old male and 51 year old female) had received renal transplants 156 and 240 months, respectively prior to onset of laryngeal symptoms. Supraglottic polypoid masses were identified and removed conservatively. Histologically, the tumors were hypercellular, showing alternating light and dark areas, the latter composed of primitive appearing round cells, while a more characteristic spindled tumor cell population was noted in the remaining areas. Cytoplasmic vacuoles were noted adjacent to the nucleus. There was no tumor necrosis or pleomorphism, but increased mitotic figures (11-12/2 mm²) were seen, without atypical forms. The tumor cells were strongly immunoreactive with smooth muscle actin and smooth muscle myosin heavy chain and with Epstein-Barr virus encoded RNA (EBER) by in situ hybridization. These patients were reviewed in the context of a thorough English literature review, which demonstrates a wide age range at presentation without a sex predilection, but with most patients from specific ethnic groups (Chinese, Thai, Pilipino). Three-quarters of patients are part of multifocal disease and the majority are post-renal transplantation patients. Conservative management seems to yield the best overall outcome for these indolent tumors. In conclusion, EBV-associated smooth muscle tumors should be considered in any immunocompromised patient with a head and neck smooth muscle tumor, especially when EBER is documented by in situ hybridization. Conservative management may be employed, even when multifocal tumors are documented.

Pediatric laryngeal inflammatory myofibroblastic tumour: Case report and systematic review of the literature

INTRODUCTION

Inflammatory myofibroblastic tumours (IMT) are rare benign neoplasms in the pediatric population, found most frequently in the lungs with rare reports of laryngeal involvement. The aim of this paper is to present a clinical case of laryngeal IMT followed by a systematic review on pediatric laryngeal IMT.

CASE REPORT

We present the case and the management of a 13-year-old boy with a laryngeal IMT MATERIAL AND METHODS: A comprehensive review of literature was conducted in September 2019 using Pubmed and Scopus. Included articles were reviewed for mean age at presentation, gender, main symptoms, treatment modality, histopathological features and follow-up RESULTS: Sixteen cases of pediatric laryngeal IMT were reported in the literature. The mean age of presentation was 7 years; endoscopic surgical resection was used in 87% of procedures, and the mean number of interventions needed to achieve remission was 1.6.

CONCLUSIONS

Pediatric laryngeal IMT are rare benign proliferations with only 16 reported case in the medical literature. The diagnosis of this entity remains a challenge and the standard of care is surgery with clear margins.

A Novel ALK-THBS1 Fusion in a Laryngeal Inflammatory Myofibroblastic Tumour: A Case Report and Literature Review

Inflammatory myofibroblastic tumor (IMT) is an uncommon neoplasm most frequently seen in the abdomino-pelvic region and lungs of children and young adults. Laryngeal tumors are rare. We present a case of a 23-year-old patient with a 5 month history of laryngitis and aphonia unresolved by corticotherapy. Laryngoscopy revealed a small, non-ulcerated, subepithelial, polypoid mass arising from the right vocal cord. The diagnosis of IMT with ALK expression was supported by histopathologic and molecular analysis. The THBS1 fusion partner was identified by RNA-sequencing analysis for the first time in a laryngeal IMT. This fusion partner has only been identified in six uterine IMTs thus far. Conservative excision of the lesion yielded excellent functional results for the patient. The voice was preserved and no recurrences were seen after 6 months of follow-up.

Vocal cord inflammatory myofibroblastic tumor with mucoid deposits harboring TIMP3-ALK fusion: A potential diagnostic pitfall

A 35-year-old Japanese man who had experienced hoarseness for 10 years presented with a vocal cord lesion. A gross examination revealed a left vocal cord polyp occupying two-thirds of the vocal space. The endoscopically resected lesion contained scattered atypical fibroblastic, stellate, or ganglion-like cells with mucoid stroma. Vacuolated cells were also seen. Lymphoplasmacytic infiltrate was largely undetectable. A vocal cord polyp was first suspected, but well-differentiated liposarcoma and inflammatory myofibroblastic tumor (IMT) were included in the differential diagnoses. The tumor cells were positive for anaplastic lymphoma kinase (ALK), calponin, and vimentin, and negative for other smooth muscle markers by immunohistochemistry. Structures resembling myofibroblasts were not observed by electron microscopy, which confirmed abundant rough endoplasmic reticulum in the tumor cells and accumulated lipid droplets in some tumor cells. ALK gene rearrangement was detected by fluorescence in situ hybridization, and TIMP3-ALK fusion was confirmed by 5' rapid amplification of cDNA ends. We diagnosed the lesion as an IMT, and an ALK-rearranged stellate cell tumor may be postulated. This is the first report of a fusion partner gene of ALK in a case of laryngeal IMT.

Ear and Temporal Bone Pathology: Neural, Sclerosing and Myofibroblastic Lesions

Neural, sclerosing, and myofibroblastic lesions of the ear and temporal bone present diagnostic challenges for both clinicians and pathologists due to significant overlap in their clinical presentations, histologic appearances, and immunohistochemical profiles. While some of these lesions, such as schwannomas, are relatively common, others are rendered even more difficult because they are encountered very rarely in routine surgical pathology practice. This review is intended to provide an update on the pathology of some of the most commonly encountered primary diagnostic entities for the ear and temporal bone, and includes the following neural lesions: schwannoma, meningioma, and encephalocele/meningocele. Sclerosing lesions that will be discussed include spindle cell and sclerosing rhabdomyosarcoma, sclerosing epithelioid fibrosarcoma, and sclerosing paraganglioma. Finally, myofibroblastic lesions that will be reviewed are nodular fasciitis, IgG4-related disease, and solitary fibrous tumor. For each of these lesions, the differential diagnosis and useful ancillary tests will be discussed in the context of a broad range of additional primary and secondary lesions.

A sensitive and high throughput TaqMan-based reverse transcription quantitative polymerase chain reaction assay efficiently discriminates ALK rearrangement from overexpression for lung cancer FFPE specimens

OBJECTIVES

ALK fusion gene is an oncogenic driver in lung cancer with low prevalence, which can be ameliorated by crizotinib. Currently, ALK fusion gene can be diagnosed by fluorescence in situ hybridization (FISH) and immunohistochemistry (IHC), but inconstistnt results between the two methods are encountered regularly. To make the ALK fusion gene screening more efficient and to provide a simple solution to clarify the discrepancy between FISH and IHC results, a sensitive TaqMan-based reverse transcription quantitative polymerase chain reaction (RT-qPCR) assay was established.

MATERIALS AND METHODS

The 3-plex TaqMan-based RT-qPCR assay was established and performed on 102 archived formalin-fixed, paraffin-embedded (FFPE) NSCLC samples to detect ALK rearrangement and overexpression. Break-apart FISH and automatic immunohistochemistry based ALK assays were performed side by side using tissue microarray.

RESULTS

The RT-qPCR was performed successfully for 80 samples and 10 of them showed positive signals. Three out of the 10 qPCR positive cases were further confirmed by FISH and IHC test. Two others were IHC positive and FISH negative, and expressed full-length ALK transcript. The rest were neither FISH nor IHC positive and their ALK expression level was significantly lower than those FISH or IHC positive cases.

CONCLUSION

Our RT-qPCR assay demonstrates that the capability and reliability of ALK detection is comparable to FISH and IHC, but it is more effective at discriminating ALK rearrangement from overexpression. The RT-qPCR assay easily clarifies the discrepancy between FISH and IHC, and can be incorporated into routine ALK screening for lung cancer.