AMYLOID GOITER IN FAMILIAL MEDITERRANEAN FEVER (FMF): A CLINICOPATHOLOGIC STUDY OF 10 CASES

Abstract

FMF Amyloidosis is an important etiological factor of end stage renal disease (ESRD) in Mediterranean Countries. Apart from major target organs as cardiovascular, respiratory and gastrointestinal system, endocrine organs can also be involved. We planned to investigate the thyroid involvement in our amyloidosis group. The aim of this study was to determine clinical characteristics of amyloid goiter in FMF patients and the abnormalities of thyroid function, as well as to identify pathologic characteristics. Twenty-two hemodialysis patients (mean age 34.1 ±14 years, range 17–68) whose ESRD secondary to FMF amyloidosis were evaluated with physical examination, serum levels of thyroid hormones, ultrasound examination of thyroid glands, thyroid syntigraphic studies. Goiter was found in 10 patients (4 male, 6 female) having enlarged neck mass (mean age 35 ± 14 years, range 23–64). The serum levels of thyroid hormones and TSH were normal in 4 patients. Other four cases had euthyroid sick syndrome. Only one patient developed tender enlarged neck mass with subacute thyroiditis symptoms and one had primary hyperthyroidism. Ultrasound examination showed; hypoecoic nodules in 6 patients diffuse multinodular enlargement in 4 patients. Thyroid syntigraphic studies revealed hypoactive nodules in 7 patients and hyperactive nodules in 3 patients. After the laboratory tests were completed, in 10 patients diagnosis were made with fine needle aspiration biopsy. Of 10 patients 5 underwent subtotal thyroidectomy. Immunohistochemical evaluation demonstrated the presence of amyloid AA immunoreactivity in all cases. In conclusion fine needle aspiration from the thyroid when enlarged is useful in the diagnosis of suspected amyloidosis, especially since it is a safe, easily performed procedure. With the help of amyloid goiter diagnosis the patient's prognosis on hemodialysis and with renal transplantation can be predicted. Amyloid goiter must be searched in hemodialysis patients especially in Mediterranean Countries.

• Amyloidosis
• Goiter
• FMF

INTRODUCTION

Amyloidosis characterized by the accumulation of an amorphous material in various organs and tissue of the body is associated with a variety of inflammatory, immune, infectious, hereditary, and neoplastic conditions. One of the most important causes of amyloidosis is Familial Mediterranean Fever (FMF) seen in especially Mediterranean countries such as Turkey and Israel [1-2]. FMF is a recurrent inflammatory disease of autosomal recessive inheritance that is characterized by episodic fever and inflammation of serosal surfaces, including the peritoneum, pleura, and synovial membrane [[3]]. FMF is associated with widespread deposition of amyloid in tissues, and is indistinguishable from reactive systemic amyloidosis. Although the most involvement of amyloidosis is seen in kidney, liver, bone marrow, subcutaneous fat tissue, and rectal mucosa, diffuse and clinically apparent enlargement of the thyroid gland due to widespread amyloid deposit is rare occurrence. Amyloid infiltration of the thyroid secondary to FMF has been reported only rarely in the English literature [4-8]. Amyloid goiter is seen in about 30–80% of patients with secondary amyloidosis, and in 50% of those with primary amyloidosis [[5]]. Amyloid goiter is manifested by progressive enlargement of the thyroid gland that is often asymptomatic initially. Patients first notice a nodular or diffuse enlargement confined to one lobe of the gland, and this spreads fairly rapidly to involve the isthmus and the opposite lobe. Widespread amyloid deposition in the thyroid gland causes diffuse clinically apparent enlargement of the thyroid, which leads to local symptoms of dyspnea, dysphagia, hoarseness, and choking spells [[5]]. Approximately 250 cases of amyloid goiter have been reported. Thyroid function has been normal in most instances [6-7]. Whereas, hyperthyroxinemia and hypothyroidism have been found in few cases [[8]]. At our clinic, we have seen 10 cases of amyloid goiter secondary to FMF. The aim of this study was to determine clinical characteristics of amyloid goiter in FMF patients and the abnormalities of thyroid function, as well as to identify pathologic characteristics.

MATERIALS AND METHODS

This study included 22 patients with AA types amyloid nephropathy secondary to FMF who were treated for renal failure at Baskent University Hospital. The diagnosis of amyloidosis in all these patients was based on histological findings from rectal, gastric, or renal biopsy. All of these patients were on chronic hemodialysis program and three of them were renal transplantation patients with non-functional graft. All these patients were evaluated for the presence of goiter. Physical examination, serum levels of thyroid hormones, ultrasound examination and thyroid scintigraphy were done. Using physical findings, we categorized each patient's goiter based on World Health Organization guidelines [[9]], as follows: Stage 0 = patients with no goiter; Stage 1A = goiter palpable but not visible; Stage 1B = goiter palpable but visible only when neck fully extended; Stage 2 = goiter easily visible with neck in normal position; Stage 3 = very large goiter. Thyroid function tests, ultrasound examination and syntigraphic studies were carried out only in patients with thyroid enlargement. Ultrasound examination was performed with Siemens Sonoline Versa Pro (Siemens, Germany). Syntigraphic studies were done with ^99mTc and gamma camera. In this group, we measured the serum levels of free T3, free T4, and TSH in each patient. Micro particle enzyme immunoassay (MEDIA) was used to determine the circulating free T3, free T4, and TSH (Abbott AxSYM system, IL, USA). The normal ranges for these are as follows: FT3: 1.6–3.5 nmol/L, FT4: 0.71–1.85 nmol/L, TSH 0.3–5 mU/L). For the quantitative determination of antithyroglobulin and antimicrosomal auto antibody was done with immunometric enzyme immunoassay (Orgentec, diagnostika Gmbh, Germany). The diagnosis of amyloid goiter was based on analysis of fine-needle aspirate (FNA) from thyroid tissue, and subtotal thyroidectomy of thyroid gland. After fine-needle aspiration, smears were air-dried and slides were stained with hematoxylin-eosin, crystal violet, and Congo red. The tissues obtained from thyroidectomy specimens were fixed in 10% Formalin and embedded in paraffin. Sections of 4 µm thickness were cut from the paraffin blocks and stained with hematoxylin-eosin, crystal violet, and Congo red to assess for distribution of amyloid deposits. In biopsies which showed amyloid deposition were examined immunohistochemically using the streptavidine-biotin peroxidase method with amyloid A, kappa, lambda, β₂ microglobulin, and transthyretin monoclonal antibodies.

RESULTS

Clinical thyroid enlargement and pathological amyloid goiter were found in 10 out of 22 patients (45.4%). The mean age of these 10 (4 male, 6 female) patients was 35.7 ± 14 years (range 23–64). Nine patients had a non-tender mass in the neck. One patient had developed a tender neck mass with subacute thyroiditis-like clinical symptoms. The characteristics of thyroid enlargement were as follows; stage 1A in 3 patients, stage 1B in 3 patients, stage 2 in 3 patients, and stage 3 in 1 patient. Ultrasound examination of 10 of the affected thyroid glands showed hypoechoic nodules in 6 cases and diffuse multinodular gland enlargement in the other 4 individuals. Thyroid scintigraphic studies revealed hypoactive nodules in seven of the patients and hyperactive nodules in three. Table 1 lists the relevant patient characteristics.

Table 1. Characteristics of the 10 Patients with Amyloid Goiter

Case No.	Age	Sex	Gland Size	Onset of FMF	Age at Diagnosis of Amyloidosis	Therapy	Symptoms	Goiter Size
1	50	M	ND	1978	1988	(–)	Dyspnea	1B
2	36	F	ND	1989	1996	(–)	Dyspnea	1A
3	25	F	RL : 9 × 8 × 5 cm	1984	1991	Surgery	Dyspnea	1B
4	20	F	RL : 7 × 4 × 2 cm	1990	1997	Surgery	Dyspnea Dysphagia	2
			LL : 9 × 5 × 4 cm
5	30	M	RL : 12 × 7 × 4 cm	1980	1987	(–)	Dyspnea Dysphagia	3
			LL : 9 × 6 × 3 cm
6	27	F	ND	1983	1993	(–)	Dyspnea	1A
7	54	M	ND	1978	1991	(–)	Dyspnea	1A
8	22	F	RL : 8 × 6 × 3 cm	1984	1991	Surgery	Dyspnea	1B
			LL : 4 × 3 × 2 cm
9	28	M	RL : 12 × 7 × 3 cm	1983	1988	Surgery	Dyspnea Dysphagia	2
			LL : 10 × 7 × 4 cm
10	27	F	RL : 13 × 11 × 5 cm	1988	1993	Surgery	Dyspnea Dysphagia	2
			LL : 2 × 2 × 1 cm

Table 2 lists the results for serum free T3, free T4 and TSH levels in the 10 patients. The patients who had normal free T3, free T4, and TSH levels were defined as euthyroid. In addition, sick euthyroid syndrome was defined as normal TSH level in spite of a low value of T3. The diagnosis of subacute thyroiditis-like syndrome was based on the findings of thyroidal pain and tenderness, inflammation, transient low thyroidal uptake of radionuclide, and increase of serum antithyroglobulin autoantibody and antimicrosomal autoantibody. Four cases were euthyroid, four of them had sick euthyroid syndrome. One patient had transient subacute thyroiditis-like syndrome and one had primary hyperthyroidism.

Table 2. Thyroid Function of 10 Patients with Amyloid Goiter

Case No.	FT3 nmol/L	FT4 nmol/L	TSH mU/L
1	1.4	0.97	1.84
2	1.2	0.75	3.5
3	3.9	1	0.1
4	2.46	1.14	0.17
5	2.8	1.17	0.52
6	1.31	1.67	1.73
7	1.64	0.72	2.7
8	1.3	1.16	0.4
9	3.26	1.2	0.4
10	2.8	1.5	0.4

FNA biopsies were obtained from 10 of the patients. Based on clinical findings, five patients underwent subtotal thyroidectomy. Cytological examination of air-dried, hematoxylin-eosin stained smears revealed abundant irregular fragments of pink-staining amorphous material in all cases. The material was more solid and hyaline-like than colloid in nature. The smears stained with Congo red were examined under polarized light, and positively stained amyloid strands exhibited the characteristic apple-green birefringence.

In addition to smears, we examined thyroid tissues obtained from surgical specimens. Macroscopically, the surfaces of all thyroid gland specimens were nodular. The majority of the nodules were firm and other nodules were of a soft gelatinous consistency. The cut surfaces of two surgical specimens were homogeneous in appearance, varied from gray-white to light brown or pale yellow in colour, and had a glassy sheen. The cut surfaces of the other three surgery specimens showed lobulation, with nodules varying from a few millimetres to several centimetres in diameter, and forming a waxy and gray-white to haemorrhagic and cystic appearance. Microscopically, the most striking feature was the complete or almost total replacement of the thyroid parenchyma with large masses of cellular, amorphous, hyaline-like material. Amyloid was deposited in the interstitial spaces around the remnants of follicular epithelium and on the walls of blood vessels. The interstitium was broadened and the follicles were stretched and lined with flattened thyroid epithelium. Foci of hyperplastic thyroidal tissue were observed but were not common.

The tissue from cases 4, 5 and 9 showed diffuse lymphocytic infiltrate and the formation of lymphoid follicles between scattered thyroid follicles. There were no giant cells in case 4, but there were scattered multinucleated giant cells in case 5 and 9. Four of these 5 patients who underwent subtotal thyroidectomy showed large amounts of adipose tissue filled the spaces between sites of amyloid deposition. A close relationship was found between interstitial amyloid deposition and interstitial adipose infiltration. In the slides stained with Congo red, the amyloid in the thyroid tissue was brick red in colour, and exhibited birefringence under polarised light. Immunohistochemical evaluation of all cases demonstrated the presence of amyloid AA.

DISCUSSION

Most of patients with FMF developed ESRD secondary to type AA amyloidosis in young age [[1]], [[10]]. On the other hand, diagnosis of amyloidosis show that the poor survival of patients on hemodialysis as well as with renal transplantation [11-13] so diagnosis of amyloidosis becomes more important in respect to survival of these patients.

Both primary and secondary amyloidosis can involve the thyroid gland. Amyloid deposition in thyroid tissue is rare, but leads to enlargement of the gland when it occurs [[5]]. Amyloid enlargement of the thyroid presents a number of diagnostic challenges for clinicians and pathologists. One possible explanation for rapidly progressive goiter and associated local symptoms is cancer of the thyroid. In these cases, demonstration of amyloid by FNA of the thyroid gland is an excellent tool that may help to explain the enlargement of thyroid. Thyroid gland enlargement can also result from urinary loss of thyroid hormones, exposure to goitrogens, or iodine deficiency [[14]]. All of our patients had end-stage renal failure, and thus were excreting very small volumes of urine per day. None had been exposed to goitrogens, and none had iodine deficiency. Thus, the only explanation for gland enlargement in our cases was amyloid deposition. In respect of the thyroid function, thyroid hormone levels were mostly within normal limits in the patients with amyloid goiter [6-7]. But recent studies have revealed various thyroid abnormalities in these patients, including both hyperthyroxinemia and hypothyroidism [14-16]. Kimura et al reported thyroid dysfunction including thyrotoxicosis and hypothyroidism in 90% of patients who had amyloidosis secondary to rheumatoid arthritis [[16]]. In addition five Japanese patients with amyloid goiter were also reported to have subacute thyroiditis-like syndrome [[17]]. However, the majority of our patients were clinically and biochemically euthyroid. Only one of our patient with amyloid goiter had symptoms that indicated subacute thyroiditis and one patient had primary hyperthyroidism.

Various ultrasonographic images have been described in patients with thyroid amyloidosis secondary to FMF [[18]]. Focal amyloid deposition is detected as complex or hypoechoic masses. Some of our patients had hypoechoic masses, but in others the thyroid gland contained hyperintense areas or had a nodular appearance. When the goiter was first observed in these patients, ultrasound showed that the gland was homogeneous, but follow-up sonography showed heterogeneous enlargement.

Histopathological study has shown that fatty tissue is sometimes seen along with amyloid deposition [[5]]. This has been observed exclusively in cases of amyloid goiter, and not in other conditions in which amyloid is deposited in the thyroid, such as medullary carcinoma. Mature fat was present in five of seven cases of amyloid goiter described by Kennedy et al. [[3]], and the adipose tissue exhibited a consistent topographic relationship with the stromal amyloid. We observed mature fat cells in the histopathology sections from four patients. The possible mechanism of interstitial fat cell infiltration in thyroid was suggested as a metaplastic process. It was suggested that fibroblastic cells in the interstitium were change into mature fat cells in cases with interstitial amyloidosis.

A chronic inflammatory infiltrate composed of lymphocytes and plasma cells is a consistent histopathological finding in the thyroid glands of patients with amyloid goiter. Also, multinucleated giant cells may be found at the periphery of the amyloid deposit [[5]]. We observed mild to moderate lymphocytic infiltrates in three of our cases and multinucleated giant cells were present only in two patients. No significant relationship was reported between interstitial mononuclear cell infiltration and interstitial amyloidosis.

In conclusion, although it is rare, thyroid involvement in amyloidosis secondary to FMF does occur. Diagnosis of amyloidosis is important to predict the survival of ESRD patients who are on hemodialysis or have renal transplantation. Although the thyroid shows diffuse amyloid involvement and wide spread fatty changes, most of the patients were euthyroid. FNA of the enlarged thyroid gland is a safe and simple procedure, which provides the diagnosis of primary or secondary amyloidosis. Attention to cell morphology and to the features of the accompanying amyloid allows the physician to differentiate amyloid enlargement of the gland from medullary carcinoma, and thus avoid unnecessary surgery.