DIAGNOSTIC DILEMMAS Section Editor: Prabodh Gupta

Lipomas of Anterior Neck Simulating Thyroid Nodules: Diagnosis by Fine-Needle Aspiration Sheila L. Butler, M.D., and Yolanda C. Oertel, M.D.

The anterior neck is an unusual location f o r lipomas. Cervical lipomas can be mistaken f o r non-functioning thyroid nodules. We report eight cases from our jiles diagnosed by jine needle aspiration (FNA). Our purpose is to call attention to this simple technique in establishing an accurute diagnosis and how it can contribute to better patient management by avoiding unnecessary thyroid suppres.rive therapy and/or surgery. We advocate using FNA as the initial diagnostic test on palpable masses in the neck. The differential diagnosis must include thyroid lipomatosis, thyrolipomu or adenolipoma, umyloid goiter with fatty injiltration, andfht-containing thyroidal neoplasms (papillary carcinoma and follicular neoplasms). Diagn Cytopathol 1992;8:528-53 1 . (c)

1992 Wiley-Liss, Inc.

Key Words: Thyroid nodules; Neck masses; Cytology

We report eight cases of lipomas of the anterior neck diagnosed by fine needle aspiration (FNA) at The George Washington University Medical Center. These eight patients were referred to us for palpable masses or nodules thought to be thyroidal in origin. There is no consensus on the diagnostic approach to thyroid nodules. However, in the last few years more emphasis is being placed on using FNA as the initial diagnostic tool. The savings accomplished with this technique, its simplicity, its lack of morbidity, and the diagnostic accuracy3r4 are well known. In spite of all these advantages, we believe FNA is not being utilized to its full potential.

Patients, Methods and Results In 1976 we introduced the technique of FNA at our institution. Lesions of the breast were the most common aspirations, followed by thyroid lesions. Since 1984 thyroid ~

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Received December 16, 1991. Accepted January 31, 1992. From the Department of Pathology, George Washington University Medical Center, Washington, D.C. Address reprint requests to Sheila L. Butler, M.D., Pathology Department, Km. 2221-South, The George Washington University Medical Center, Washington, D C 20037.

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Diugriostic Cytopathology, Voi 8, No 5

nodules are the most frequently aspirated lesions in our Cytopathology Service. We have over 7,000 thyroid aspirates in our files; of these, eight were referred to us as thyroid masses, but we diagnosed them as lipomas of the neck by FNA. There were six men and two women, ranging in age from 34 to 67 years (see Table I). The patients presented with anterior cervical masses varying in size from 2.5 cm to 8.5 cm in greatest dimensions (Figs. 1, 2). All eight patients were aspirated by pathologists. Multiple aspirations were performed on each patient using a Cameco syringe holder, 10 cc disposable syringes, and 22 gauge needles (1 and 1!h inches long) with clear plastic hubs. We have described in several publications the technique used. 5,6 After each aspiration one smear was stained with Diff-Quik and examined immediately through the microscope to determine adequacy of the specimen. The aspirations were repeated with a minimum of three FNAs per patient, using longer needles (1% inches). All smears showed many fragments of mature adipose tissue (Figs. 3, 4). No follicular epithelial cells were present.

Discussion Subcutaneous or superficial lipomas are the most frequent benign soft tissue tumors. They occur in older individuals (fifth and sixth decade of life), most commonly in the back, shoulders, posterior neck, and abdomen. They have been reported in the anterior neck on rare occasions. 7-9 Thyroid lesions containing adipose tissue are relatively rare. The following have been reported: 1. Hamartomatous adiposity also known as choristomatous adiposity, diffuse lipomatosis, fatty infiltration, or heterotopic nests of fat cells. This entity consists of diffuse deposits of mature fatty tissue within the thyroid parenchyma. Probably it is a congenital anomaly in which the adipose tissue is incorporated within the thyroid gland during embryogenesis, or a metaplastic transformation of the stroma. ' -I3

FNA OF CERVICAL LIPOMAS Table I.

Eight Patients With Lipomas of Anterior Neck Simulating Thyroid Nodules"

34/M

None

None

2 5 em

I\thmu\

Not available

Cold nodule

Not obiaiiied

Within irornral

42/M

None

None

5.0 em

R anterior neck

Euthyroid

Not obtained

Not obtained

Not ohtamed

64/M

Noiic

L ihyroidectoniy 1974, benign

4.0 cm

R lower neck

Euth) riiid on rrpidceinrnt K x

Not obtained

Not obtained

Not obtained

41/M

None

None

4.0 e m

R upper thyroid

Euthyroid

Normal

Not obtained

Normal

Euthyroid

Cold nodule

Not obtained

Not obtained

I\io change Surgical c x c i \ i o n

limiib

N o change

lobe

39/M

Noric

None

4.0 cm

L anterior neck

6S/F

Incrcaw in w e of neck

Euihyroid goiter

8.5 cm

L anterior neck

Euihyroid

Not obtained

Left carotid sheath liponia

Bilateral hyperechogenic

39/M

None

None

3 0 em

L anterior neck

Euthyroid

Normal

Extrathyroid lipoma

Not obtained

N o change

67/F

Dyjphagia

R thyroidectomy

4 8 em

L anterior neck

Euthyroid

Cold nodule

Not obtained

Not obtained

N o change

maws

1957, benign

"K

righi: I- = left. hTFT = thyroid function test\. 'Cf = conrpuierized tomography. 1

2 . Thyrolipoma also known as adenolipoma, adipose tissue in adenoma of the thyroid, or adipose metaplasia in thyroid adenoma. It probably represents a true neoplasm. This is a well-circumscribed lesion which consists of a mixture of mature adipose tissue and neoplastic thyroid follicles. Cytologic findings have been reported in one of these cases, retrospectively, as the original aspirate was not interpreted correctly. 22 3. Fat-containing non-neoplastic conditions, such as amyloid goiter, lymphocytic thyroiditis, dyshormonogenetic goiter, and thyroid atrophy. 23,24 4. Fat-containing thyroid neoplasms, such as papillary carcinoma, follicular adenoma, and follicular carcinoma with variable amounts of mature adipose tissue replacing their stroma.24,25 5. Lipid-rich follicular cell lesions, a type of clear cell adenoma and carcinoma of the thyroid, in which the neo-

Usually, when aspirating thyroid masses, no adipose tissue from the subcutis is obtained, unless the patient is obese and a short needle has been used. A possible pitfall on submitted smears is misdiagnosing subcutaneous fat as cervical lipoma, as cytologically they are identical. This can be avoided if the pathologist performs the aspiration. The pathologist can insert multiple needles, of different lengths, in different parts of the lesion. Otherwise, if only adipose tissue is observed in submitted smears, the pathologist should ask the referring physician if the lesion is consistent with a lipoma on clinical evaluation.

Fig. 1. Thirty-nine year old man with a left anterior neck mass.

Fig. 2. Sixty-seven year old woman with a left anterior neck mass.

plastic follicular cells contain lipid droplets which impart a clear or vacuolated appearance to their cytoplasm. '3,26 6. Liposarcoma, a malignant soft tissue tumor of which only two cases arising in the thyroid have been reported. 27928

Diagnostic Cytoputhology, Vol 8. No 5

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BUTLER AND OERTEL

Fig. 3. Large fragments of mature adipose tissue from lipoma of anterior neck. (FNA, Diff-Quik stain, X 100.)

I

Fig. 4. Fragment of adipose tissue from lipoma traversed by capillaries (FNA, Diff-Quik stain, X 160.)

Palpable anterior cervical mass on physical examination (In lhyroid. extrinsic lo thyroid. indelerminate)

Adipose tissue only

Adipose tissue mixed with follicular cells

I

Thyroid elements only

1

Benign

i

I ~~

Hamartomatous adiposity

~

Inconclusive (e.g. follicular neoplasia)

Thyrolipoma

Malignant

Surgery if cosmetic or physiologic problems I

Further steps as appropriate for management of thyroidal disease

Surgery I

I

Fig. 5. Decision chart for the management of palpable anterior neck masses.

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Oiugrro~ticCyropathology. Vol 8, No 5

FNA OF CERVICAL LIPOMAS

Although we recognize that adipose tissue may be a part of the stroma of a malignant thyroidal neoplasm, 24*25 this is so rare that we believe it falls outside the scope of this discussion. Notably, only three cases in the literature report the use of F N A ‘ 6 , 2 2 * 2 8 as part of the diagnostic workup of these patients. The F N A in De Rienzo’s case was not helpful in establishing the subsequent diagnosis of follicular carcinoma associated with the multifocal adiposity found in the thyroid specimen. In Rollins’ case the F N A was performed on two occasions and reported as inadequate for diagnosis and negative for malignant cells, respectively. The patient underwent a right hemithyroidectomy which revealed a thyrolipoma. Further review of the FNA showed mature adipose tissue mixed with benign follicular epithelium, which in retrospect, should have raised the possibility of a thyrolipoma or adenolipoma. In Andrion’s case the FNA was interpreted as “tumor suggestive of anaplastic carcinoma of the thyroid.” Surgical excision revealed a myxoid liposarcoma. None of our cases showed follicular epithelial cells mixed with the mature adipose tissue fragments on the smears. Three patients had surgical excision of the mass which confirmed our diagnosis of lipoma. One patient has been lost to follow-up and the other four have been followed from 1 to 6 years without any change in their lesions. It has been reported that computerized tomography (CT) helps to establish the diagnosis of cervical lipomas. 29 Two of our patients had computerized tomography of the neck, and it confirmed the presence of an extra-thyroidal lipoma (see Table I). However, F N A is a simpler and less expensive way of accomplishing the same goal. We propose that an aspiration be the initial diagnostic procedure for any palpable cervical mass (see Fig. 5). Unnecessary suppressive therapy and/or surgery may be avoided.

References 1. Altavilla G , Pascale M, Nenci I . Acta Cytol (Baltimore) 1990;34:

251-256. 2. Van Herle AJ. Moderator, UCLA Conference. The thyroid nodule. Ann Intern Med 1982;96:221-232. 3. Hamherger B, Gharib H, Melton LJ, Goellner JR, Zinsmeister AR. Fine-needle aspiration biopsy of thyroid nodules. Impact on thyroid practice and cost of care. Am J Med 1982;73:381-384. 4. Miller JM, Hamburger J I , Kini S. Diagnosis of thyroid nodules. Use of fine-needle aspiration and needle biopsy. JAMA 1979;241:481484. 5. Wartofsky L, Oertel YC. Fine needle aspiration of thyroid nodules. I n : Van Nostrand D, Baum S, eds. Atlas of nuclear medicine. Philadelphia: JB Lippincott, Co., 1988;8:193-200.

6. Oertel Y C . Fine-needle aspiration of the thyroid. I n : Moore WT, Eastman RC, eds. Diagnostic endocrinology. Toronto: BC Decker. 1990;8:149-165. 7. Leonidas J-R. Lipoma of neck mimicking thyroid nodule. Lancet 1979;1:1195. 8. Leonidas J-R, Goldman JM, Wheelcr MF. Cervical lipomas masquerading as thyroid nodules. JAMA 1985;253:1436-1437. 9. Ramakantan R, Shah P. Anterior neck lipoma masquerading external laryngocoele. J Laryngol Otol 1989: 103:1087-1088. 10 Meissner WA, Warren S. Tumors of the thyroid gland. Atlas of tumor pathology, second series, FASC. 4. Washington, DC: Armed Forces Institute of Pathology, 1969:41. 11. Asirwatham JE, Barcos M, Shimaoka K. Hamartomatous adiposity of thyroid gland. J Med 1979;10:197-206, 12. Dhayagude RG. Massive fatty infiltration in a colloid goiter. Arch Pathol Lab Med 1942;33:357-360. 13. Schroder S, Bocker W. Lipomatous lesions of the thyroid gland: A review. Appl Pathol 1985;3:140-149. 14. Chesky VE, Dreese WC, Hellwig CA. Adenolipomatosis of the thyroid. A new type of goiter. Surgery 1953:34:3845. 15. DePaepe ME, Waxman M. Adenolipoma of the thyroid gland. Mt Sinai J Med 1988;55:198-200. 16. DeRienzo D, Truong L. Thyroid neoplasms containing mature fat: A report of two cases and review of the literature. Mod Pathol 1989;2:506-5 10. 17. Hjorth L, Thomsen LB, Nielsen VT. Adenolipoma of the thyroid gland. Histopathology 1986:10:91-96. 18. Pagks A, Tiraskis B. Deux cas de thyro-lipome. Ann Pdthol 1985;5: 283-286. 19. Schroder S, Bocker W, Hiisselmann H, Dralle H. Adenolipoma (thyrolipoma) of the thyroid gland. Report of two cases and review of literature. Virchows Arch [A] 1984;404:99-103. 20. Simha MR, Doctor VM. Adenolipomatosis of the thyroid gland. Ind J Cancer 1983;20:215-217. 21. Trites AEW. Thyrolipoma, thymolipoma and pharyngeal lipoma: A syndrome. Can Med Assoc J 1966;95:1254-1259. 22. Rollins SD, Flinner RL. Thyrolipoma: Diagnostic pitfalls in the cytologic diagnosis and review of the literature. Diagn Cytopathol 1991;7:150-1 54. 23. Fuller RH. Hamartomatous adiposity with superimposed amyloidosis of thyroid gland. Am J Clin Pathol 1950;20:188-189. 24. Gnepp DR, Ogorzalek JM, Heffess CS. Fat-containing lesions of the thyroid gland. Am J Surg Pathol 1989;13:605-612. 25. Vestfrid MA. Papillary carcinoma of the thyroid gland with lipomatous stroma: report of a peculiar histological type of thyroid tumor. Histopathology 1986; 10:97-100. 26. Toth K , Peter I, Krernmer T, Suglir J. Lipid-rich cell thyroid adenoma: histopathology with comparative lipid analysis. Virchows Arch [A] 1990;417:273-276. 27. Nielsen VT, Knudsen N, Holm IE. Liposarcorna of the thyroid gland. Tumori 1986;72:499-502. 28. Andrion A, Gaglio A, Dogliani N, Bosco E, Mazzucco G . Liposarcoma of the thyroid gland. Fine-needle aspiration cytology. immunohistology, and ultrastructure. Am J Clin Pathol 1991;95:675679. 29. Som PM, Scherl MP, Rao VM, Biller HF. Rare presentations of ordinary lipomas of the head and neck: A review. AJNR 1986;7: 657-664.

Diagnorric Cytoparhology. Vol 8,No 5

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Lipomas of anterior neck simulating thyroid nodules: diagnosis by fine-needle aspiration.

The anterior neck is an unusual location for lipomas. Cervical lipomas can be mistaken for non-functioning thyroid nodules. We report eight cases from...
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