ABSTRACT
Inflammatory myofibroblastic tumour (IMT) is a rare mesenchymal neoplasm that usually originates from abdominal soft tissues. A female patient aged 50 years presented with a 1.2 cm gallbladder polyp. The microscopic study showed spindle cell proliferation in an edematous background rich in lymphocytes and plasma cells. Immunohistochemistry showed positivity for vimentin, smooth muscle actin, and anaplastic lymphoma kinase (ALK), and negativity for other markers. Fluorescent in situ hybridization (FISH) revealed ALK gene rearrangement. The diagnosis was IMT of the gallbladder, a unique case considering that it was identified at the early stage of development of these neoplasms.
Key words:
gallbladder; soft tissue neoplasms; polyps
A) polypoid lesion (arrow) arising from the gallbladder wall (arrowhead), with 1.2 cm and yellowish cut section (macroscopic photograph); B) the lesion is located below gallbladder epithelium (HE stain, 40×); C) neoplastic spindle cell proliferation in a slightly oedematous background, rich in lymphocytes and plasma cells (HE stain, 100×); D) the neoplastic cells had eosinophilic cytoplasm and oval nuclei with small nucleoli (HE stain, 400×).HE: hematoxylin and eosin.
The neoplastic cells showed positive staining for vimentin (A) and smooth muscle actin (B), and negative staining for pan-cytokeratin AE1/AE3 (C) and CD117 (D). All images were captured at 200× magnification.
A) the neoplastic cells showed a cytoplasmic granular staining for ALK, 200×; B) FISH revealed rearrangement of ALK gene in 52% of the neoplastic cells studied, characterized by separation of the telomeric (red) and centromeric (green) signals of the ALK break-apart probe used.FISH: fluorescent in situ hybridization; ALK: anaplastic lymphoma kinase.