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Ossifying fibromyxoid tumor metastatic to the thyroid: a case report and review of the literature.

Abstract

Ossifying fibromyxoid tumors are rare soft-tissue neoplasms, usually with an indolent course. However, atypical/ malignant variants have been described, showing either local recurrence after complete excision or metastasis to the lungs, mediastinum, adrenals, or soft tissue. We report the case of an ossifying fibromyxoid tumor of the left ankle that metastasized to the lung and thyroid gland 12 years after the initial diagnosis and surgical treatment. To our knowledge, this is the first reported case of this neoplasm metastasizing to the thyroid gland.

Introduction

Ossifying fibromyxoid tumors of soft parts (OFMTs) are rare soft-tissue neoplasms. (1) They are usually small, painless, and well circumscribed, and commonly arise in the subcutis or muscle of the extremities; less often, they arise from the trunk or head and neck region. (1)

Microscopically, these tumors are partially lobulated, containing small, round cells with vesicular nuclei and minute nucleoli, arranged in cords within a fibromyxoid matrix. (2) A peripheral rim of collagen with metaplastic bone is commonly present, but cases lacking bone formation have been described. (3)

Although OFMTs are often benign, reports have described atypical variants that exhibit local recurrence after complete local excision, as well as distant metastasis to the lung, mediastinum, adrenals, or soft tissue.4'6 We report the case of a variant of malignant OFMT that originated in the leg and metastasized to the lung and thyroid. A single case of OFMT originating in the prethyroidal soft tissue with direct extension into the thyroid was described by Lax et al (7) in 1995, but to our knowledge, ours is the first reported case of metastatic OFMT to the thyroid.

Case report

A 55-year old woman presented with a mass in her left ankle. Biopsy of the lesion revealed an intermediate-grade sarcoma, possibly a variant of malignant OFMT. The patient underwent a left below-knee amputation, and pathology of the resection specimen confirmed this diagnosis. The margins of resection were negative for tumor. The patient had no postoperative adjuvant therapy, but she was closely followed for 12 years with no evidence of recurrence.

Twelve years after her initial OFMT diagnosis, the patient presented to an emergency department with left chest and upper shoulder pain. Initial evaluation, including a multi-gated acquisition scan, revealed no cardiac ischemia. However, chest x-ray showed a large mass in the lower lobe of the left lung with an associated pleural effusion. Biopsy of this lesion revealed a spindle-cell neoplasm, most consistent with metastatic disease from her original sarcoma.

Further workup with computed tomography of the chest, abdomen, and pelvis confirmed the presence of a lung mass measuring 11.5 x 7.2 cm. Three indistinct, smaller nodules were also found in the lung. Incidentally, a 3.6-cm nodule was seen in the thyroid isthmus. Subsequent positron-emission tomography showed a standard uptake value (SUV) in the larger, lower left lung mass of 3.5 and an SUV of 3.4 in the thyroid nodule. The smaller, indistinct masses in the lung were inactive. A bone scan was also performed and was unremarkable.

The patient underwent left lower-lobe resection; pathology on a section of the lingula revealed a low-grade fibromyxoid sarcoma consistent with metastatic disease. Further workup of the thyroid nodule with ultrasound demonstrated multiple masses, with a dominant mass measuring 2.5 cm in the right lobe of the thyroid. Ultrasound-guided fine-needle aspiration of this mass was interpreted as a follicular neoplasm, and a decision was made to perform right hemithyroidectomy and isthmusectomy.

Pathology of the thyroid revealed that the larger, more prominent mass seen by ultrasound was consistent with an adenomatous nodule. However, a distinct, 0.6-cm focus showing moderately sized epithelioid cells within a fibromyxoid background was also present. Histologically, this lesion was similar to that seen in the ankle and lung, consistent with metastatic disease.

The initial left ankle lesion was composed of areas containing bland and uniform ovoid to spindled cells with hyperchromatic nuclei distributed in a vaguely corded pattern, scattered in a collagenous matrix. Very few mitoses were present in these areas. However, other areas had much higher cellularity, with nuclear pleomorphism and scattered multinucleated giant cells. Osseous and cartilaginous metaplasia was also focally present. Given these characteristics, the lesion was classified as an intermediate-grade sarcoma, consistent with an atypical/malignant variant of OFMT.

The thyroid tumor nodule was described as a white, well-circumscribed, slightly firm nodule measuring 0.6 cm in diameter. Microscopically, this nodule was composed of moderately sized epithelioid cells with indistinct cell borders, fibrillary cytoplasm, and round to irregular nuclei with clumped chromatin within a fibromyxoid background (figure). Focally, single cell necrosis and increased mitotic activity (up to 22 mitoses per 10 high-power fields) were seen. Overall, the lung and the thyroid lesions shared similar histopathologic features, consistent with metastatic disease from the same ankle primary.

Discussion

Primary mesenchymal tumors of the thyroid are uncommon. Metastasis to the thyroid gland is a relatively infrequent finding in clinical practice, occurring in the setting of widely metastatic melanoma and carcinoma of the breast, kidney, or lung. (8) Sarcomas metastatic to the thyroid are extremely rare and occur almost exclusively in cases of malignant fibrous histiocytoma (undifferentiated pleomorphic sarcoma), leiomyosarcoma, and liposarcoma. (8-10) To our knowledge, this is the first report of OFMT metastasizing to the thyroid gland.

OFMT was first described by Enzinger et al in 1989 as a neoplasm that has a largely benign histologic appearance and clinical course, occurs in patients ranging in age from 14 to 83 years, and has a slight male preponderance. (1,11) Multiple reports have described OFMT variants with either atypical or frankly malignant histology that behave in a more aggressive manner, either with local recurrence after complete excision or with distant metastasis to various sites.

In the follow-up of 51 cases, Folpe et al found metastatic disease in 8 cases (mean follow-up time of 54 months); additional case reports have described 2 cases of OFMT metastatic to the lungs. (5,6,12) Furthermore, reports have described aggressive behavior in histologically bland-appearing tumors with metastasis and eventual death of the patient. (11,13) However, because of the rarity of this tumor, its behavior and the sites to which it metastasizes are not well characterized.

Immunohistochemical staining patterns of OFMT lesions vary greatly. Approximately 70% of OFMTs are positive for S-100 protein and vimentin, but this percentage decreases considerably in atypical and malignant variants of the disease. (2) Positivity for keratins, smooth muscle actin, collagen II, desmin, leu-7, and glial fibrillary acidic protein have also been described. (2,6)

Our patient had a known history of OFMT that was labeled as an atypical/malignant variant because of the high cellularity and nuclear pleomorphism it displayed. The pulmonary nodule appeared more than 12 years after the initial diagnosis. Since the lungs are the most common site for metastasis of these tumors, clinical suspicion for metastatic disease was high. Although the lung lesion displayed mild cellularity without pleomorphism, mitotic figures, and necrosis, the overall appearance was more consistent with metastasis rather than a separate new primary.

In conclusion, we present the case of an atypical/malignant variant of OFMT that metastasized to the lung and thyroid gland more than 12 years after the initial diagnosis. Given the largely unknown clinical behavior of and prognosis for these tumors, close follow-up of patients with OFMT is recommended.

References

(1.) Enzinger FM, Weiss SW, Liang CY. Ossifying fibromyxoid tumor of soft parts. A clinicopathological analysis of 59 cases. Am J Surg Pathol 1989;13(10):817-27.

(2.) Soft tissue tumors of intermediate malignancy of uncertain type. In: Weiss SW, Goldblum JR, John R. (eds). Enzinger and Weiss's Soft Tissue Tumors. 5th ed. St. Louis: Mosby; 2007:1093-1101.

(3.) Fisher C, Hedges M, Weiss SW. Ossifying fibromyxoid tumor of soft parts with stromal cyst formation and ribosome-lamella complexes. Ultrastruct Pathol 1994;18(6):593-600.

(4.) Miettinen M, Finnell V, Fetsch JF. Ossifying fibromyxoid tumor of soft parts--a clinicopathologic and immunohistochemical study of 104 cases with long-term follow-up and a critical review of the literature. Am J Surg Pathol 2008;32(7):996-1005.

(5.) Suehiro K, Pritzwald-Stegmann P, Lee KM, et al. Mediastinal and pulmonary metastases of malignant ossifying fibromyxoid tumor. Ann Thorac Surg 2006;81(6):2289-91.

(6.) Folpe AL, Weiss SW. Ossifying fibromyxoid tumor of soft parts. A clinicopathologic study of 70 cases with emphasis on atypical and malignant variants. Am J Surg Pathol 2003;27(4):421-31.

(7.) Lax SF, Ratschek M, Steindorfer P, et al. Ossifying fibromyxoid tumor of the neck clinically mimicking a primary neoplasm of the thyroid gland. Pathol Res Pract 1995:191(l):57-60.

(8.) Baloch ZW, LiVolsi VA. Unusual tumors of the thyroid gland. Endocrinol Metab Clin North Am 2008;37(2):297-310.

(9.) Ackerman L, Romyn A, Khedkar N, Kaplan E. Malignant fibrous histiocytoma metastatic to the thyroid gland. Clin Nucl Med 1987;12(8):648-9.

(10.) Wood K, Vini L, Harmer C. Metastases to the thyroid gland: The Royal Marsden experience. Eur J Surg Oncol 2004;30(6):583-8.

(11.) Kilpatrick SE, Ward WG, Mozes M, et al. Atypical and malignant variants of ossifying fibromyxoid tumor. Clinicopathologic analysis of six cases. Am J Surg Pathol 1995;19(9):1039-46.

(12.) Sarraj A, Duarte J, Dominguez L, Pun YW. Resection of metastatic pulmonary lesion of ossifying fibromyxoid tumor extending into the left atrium and ventricle via pulmonary vein. Eur J Echocardiogr 2007;8(5):384-6

(13.) Yoshida H, Minamizaki T, Yumoto T, et al. Ossifying fibromyxoid tumor of soft parts. Acta Pathol Jpn 1991;41(6):480-6.

From the Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, Philadelphia (Dr. Lastra); the Department of Pathology and Laboratory Medicine (Dr. Huang and Dr. Brooks) and the Department of Otorhinolaryngology, Center of Head and Neck Surgery (Dr. Newman), Pennsylvania Hospital, Philadelphia.

Corresponding author: Ricardo R. Lastra, MD, Department of Pathology and Laboratory Medicine, Hospital of the University of Pennsylvania, 3400 Spruce St., Philadelphia, PA 19104. Email: ricardo.lastra@uphs.upenn.edu
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Title Annotation:ORIGINAL ARTICLE
Author:Lastra, Ricardo R.; Newman, Jason G.; Brooks, John S.; Huang, Jui-Han
Publication:Ear, Nose and Throat Journal
Article Type:Case study
Date:Jun 1, 2014
Words:1658
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