Fine needle aspiration cytology of a granular cell tumour arising in the thyroid gland

Imaging findings of granular cell tumours of the head and neck

AIM

To review the imaging characteristics of granular cell tumours in the head and neck and assess their associations with pathological findings.

MATERIALS AND METHODS

Eleven patients (10 [91%] women, mean age 43 years) with histopathologically confirmed granular cell tumours were included in this study. Preoperative imaging studies were performed, including computed tomography (CT), magnetic resonance imaging (MRI), or ultrasound. The location of the tumours, their imaging features, and histopathological findings were analysed.

RESULTS

Among the 11 granular cell tumours, four (36%), three (27%), and two (18%) tumours were found in the submucosal layer, subcutaneous layer, and intramuscular area, respectively. On CT, all tumours exhibited homogeneous iso-attenuating enhancement compared with adjacent muscle, and nine out of the 11 tumours (81%) demonstrated well-defined margins. On T2-weighted imaging (T2WI), four out of five tumours (80%) demonstrated iso-signal intensity compared with adjacent muscles, and four tumours (80%) exhibited homogeneous signal intensity. The apparent diffusion coefficient (ADC) values ranged from 0.68-0.81 × 10-3 mm2/s. Histopathological examination revealed densely packed tumour cells with variable amounts of fibrous stroma.

CONCLUSION

Granular cell tumours were characterised by well-defined and iso-signals on T2WI and low mean ADC values, and were predominantly located in the submucosal, subcutaneous, or intramuscular areas in middle-aged women. The characteristic locations, demographic characteristics, and imaging findings can help to differentiate granular cell tumours from other soft-tissue tumours in the head and neck.

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.

Cytologic and histological features of rare nonepithelial and nonlymphoid tumors of the thyroid

Thyroid tumors can be classified into epithelial, nonepithelial, and nonprimary lesions. Nonepithelial thyroid tumors are rare. They can be of primary origin within the thyroid gland, arise secondary to contiguous growth from adjacent tissues, or represent metastatic disease. The incidence of nonepithelial tumors of the thyroid is only 1% to 2%, most of which are lymphomas; the remainder includes mesenchymal and histiocytic tumors. This review examines the cytohistological features of various nonepithelial and nonlymphoid tumors of the thyroid, including vascular lesions, neural tumors (including granular cell tumor and paraganglioma), smooth muscle tumors, solitary fibrous tumor, histiocytic neoplasms (eg, Langerhans cell histiocytosis and Rosai-Dorfman disease), and follicular dendritic cell sarcoma. Their differential diagnosis is discussed, including recommendations to prevent the pitfall of mistaking these rare tumors for more common epithelial thyroid neoplasms.

Granular Cell Tumor of Thyroid: Challenging Pitfalls and Mimickers in Diagnosis

Mesenchymal tumors of the thyroid are extremely rare. Only few isolated cases of primary thyroid granular cell tumor (GrCT) have been reported. The anatomic location of this lesion plays an important role in the differential diagnosis. It is well-known that GrCT commonly involves the head-and-neck region, lower extremity, nuchal region, chest wall, and internal viscera such as the gastrointestinal tract. However, primary GrCT of the thyroid are unexpected and might lead to misdiagnosis, especially with pathological diagnosis limitations such as frozen section and fine-needle aspiration. We believe that it is important to establish a good differential diagnosis because of its ability to simulate the appearance of invasive carcinoma, especially in cases lacking tissue block examination. In this paper, we try to focus on clinical, radiological potential characteristics, and the differential diagnosis of the tumor.

Granular-cell tumor of the anterior abdominal wall

We report a case of granular-cell tumor (GCT) arising in the subcutaneous tissue of the abdominal wall and describe its radiologic and histologic characteristics. The differential diagnosis of a mass in this site may include multiple benign and malignant stromal lesions. In this case, the presentation, location, and radiological features suggested a desmoid tumor (aggressive fibromatosis). Treatment of the mass involved surgical excision with negative margins, and histological analysis confirmed the presence of a benign GCT. We report a case of this rare, benign tumor to allow the radiologist and pathologist to consider this disease in the differential diagnosis when presented with similar cases.

Granular cell tumor of the thyroid: Clinical and pathological characteristics of a rare case in a 14-year-old girl

Granular cell tumors (GCTs) are soft tissue neoplasms that originate in the nervous system, which may arise anywhere in the body. However, GCTs are extremely uncommon in thyroid tumors, with a favorable prognosis. The diagnosis of GCTs is dependent on pathological and immunohistochemical analysis and at present, surgical resection is considered the only suitable treatment. Regular follow-up after surgery is an important way to monitor treatment outcome and recurrence. The present study describes a new pathological type of thyroid GCTs diagnosed by pathology and immunohistochemistry. A 14-year-old female was referred to the West China Hospital of Sichuan University (Chengdu, China), for thyroid incidentaloma. Laboratory examinations were within the normal range. Thyroid sonography demonstrated a solid hypoechoic mass in the right lobe of the thyroid. Fine needle aspiration cytology showed a suspicious malignant tumor and subsequently a total thyroidectomy was performed. Analysis of frozen sections, from obtained samples, did not facilitate a definite diagnosis. Finally, a thyroid benign granular tumor with atypical changes was diagnosed by postoperative pathology and immunohistochemistry. A 14-month post-operative follow-up showed that the patient experienced a stable recovery and had no signs of recurrence or metastasis. The case emphasizes that the diagnosis of thyroid granular cell tumors is predominantly based on postoperative morphology and immunophenotype. The clinical routine for the differential diagnosis may be due to: (i) neoplasms displaying a granular appearance mimicking granular cell tumors, or (ii) differential diagnosis in the pathological category of granular cell tumors. Further accumulation of such rare cases may be of clinical significance in aiding the diagnosis and treatment of GCTs.

Is fine needle aspiration cytology a useful diagnostic tool for granular cell tumors? A cytohistological review with emphasis on pitfalls

Background:

Granular cell tumors (GCT) formerly known as Abrikossoff tumor or granular cell myoblastoma, are rare neoplasms encountered in the fine needle aspiration (FNA) service. Named because of their highly granular cytoplasm which is invariably positive for the S-100 antibody, the classic GCT is thought to be of neural origin. The cytomorphological features range from highly cellular to scanty cellular smears with dispersed polygonal tumor cells. The cells have abundant eosinophilic granular cytoplasm, eccentric round to oval vesicular nuclei with small inconspicuous nucleoli. The fragility of the cells can result in many stripped nuclei in a granular background. The differential diagnosis occasionally can range from a benign or reactive process to features that are suspicious for malignancy. Some of the concerning cytologic features include necrosis, mitoses and nuclear pleomorphism.

Methods:

We identified 6 cases of suspected GCT on cytology within the last 10 years and compared them to their final histologic diagnoses.

Results:

Four had histologic correlation of GCT including one case that was suspicious for GCT on cytology and called atypical with features concerning for a malignant neoplasm. Of the other two cases where GCT was suspected, one showed breast tissue with fibrocystic changes, and the other was a Hurthle cell adenoma of the thyroid.

Conclusions:

These results imply that FNA has utility in the diagnosis of GCT, and should be included in the differential diagnoses when cells with abundant granular cytoplasm are seen on cytology. Careful attention to cytologic atypia, signs of reactive changes, use of immunohistochemistry, and clinical correlation are helpful in arriving at a definite diagnosis on FNA cytology.