Recurrent granular cell tumor of the thyroid: a case report and literature review

Malignant granular cell tumor in the thoracic wall: A case report

Granulosa cell tumor (GCT) is a rare tumor that originates from neural/Schwann cells. GCTs can occur at any age and at any site in the body. The most common site is the tongue, followed by the mammary gland, upper respiratory tract ( throat and bronchus), and gastrointestinal tract (esophagus, large intestine and perianal area, stomach, small intestine, and bile duct). Malignant GCTs account for less than 1%–2% of all GCTs. Fewer than five GCTs in the thoracic wall have been reported, almost all of these benign. Here, we report a new case of malignant GCT of the thoracic wall, with rib invasion and pleural metastasis, in an Asian male. Microscopic examination revealed round, granular cells with eosinophilic cytoplasm and without prominent atypia. Despite these findings the disease showed rapid clinical progression. In summary, the tumor, although histologically ‘benign’, was clinically ‘malignant’.

Granular cell tumor of thyroid: a case series with molecular characterization highlighting unique pitfalls

Primary granular cell tumors (GCTs) of the thyroid are exceptionally rare. We report the clinicopathologic and molecular features of three cases and review the literature. Two patients (20-year-old, Case 1, and 26-year-old, Case 2, black American females) presented with painless masses with a preoperative fine-needle aspiration biopsy (FNAB) diagnosis of "Hürthle cell neoplasm," while one additional patient, 51-year-old white American female (Case 3), presented as an incidental finding within a background of chronic lymphocytic thyroiditis. On resection, morphologic, histochemical and immunohistochemical features were typical of GCT in all cases. Cases 1 and 2 had adequate material for molecular testing and demonstrated a clonal ATP6AP1 p.G381Vfs*15 frameshift mutation (Case 1) and a clonal ATP6AP2 p.L182Pfs*22 frameshift mutation along with a PIK3CA H1047R hotspot mutation (Case 2). All patients showed no evidence of GCT following resection (Cases 1, 3: 96-month follow-up; Case 2: 48-month follow-up). A literature review demonstrates similar clinicopathologic features and indolent course with only rare histologically or clinically aggressive outcomes. On FNAB, lesional cells are frequently miscategorized as Hürthle cells or oncocytes. In summary, GCT of the thyroid is rare but shows similar clinical, morphologic, immunophenotypic and genetic characteristics of GCT of other sites. This unusual site poses unique differential diagnostic pitfalls by mimicking other oncocytic head and neck lesions, particularly thyroid Hürthle cell neoplasms. We confirm that thyroid GCT also harbor V-ATPase component inactivating mutations that characterize these tumors, and that additional PI3K pathway alterations may not necessarily predict aggressive behavior.