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

Abstract

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.

Keywords: ALK–THBS1 fusion; Anaplastic lymphoma kinase; Immunohistochemistry; Inflammatory myofibroblastic tumor; Laryngeal tumor.

Fig. 1

a Coronal fat saturation T1-weighted post contrast MRI shows thickening of the right true vocal fold (arrow). b MRI axial scan shows a soft tissue mass arising from the right vocal cord (arrow)

Fig. 2

a Photomicrograph of the tumor specimen showing myxoid tumour composed of spindle-shaped myofibroblasts with scattered inflammatory cells (haematoxylin and eosin stain, magnification ×400). b Microscopic sections show a dense spindle cell proliferation associated with a lymphoplasmacytic infiltrate (haematoxylin and eosin stain ×400)

Fig. 3

Immunohistochemical findings. The spindle cells were positive for a α-smooth muscle actin (SMA) and b anaplastic lymphoma kinase-1 (ALK-1) (immunohistochemistry staining ×200)