Postoperative spindle cell nodule after thyroidectomy: A case mimicking recurrence with anaplastic transformation of thyroid cancer

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1 CASE REPORT Postoperative spindle cell nodule after thyroidectomy: A case mimicking recurrence with anaplastic transformation of thyroid cancer Sun Wook Kim, MD, PhD, 1 Young Lyun Oh, MD, PhD, 2 Joon Young Choi, MD, PhD, 3 Ji In Lee, MD, 1 Jae Hoon Chung, MD, PhD, 1 Jee Soo Kim, MD, PhD 4 1 Division of Endocrinology and Metabolism, Department of Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea, 2 Department of Pathology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea, 3 Department of Nuclear Medicine, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea, 4 Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. Accepted 16 February 2011 Published online 22 November 2011 in Wiley Online Library (wileyonlinelibrary.com). DOI /hed ABSTRACT: Background. Here, we report a case of a postoperative spindle cell nodule that mimicked recurrence with anaplastic transformation after thyroidectomy. Methods. The course of the disease is described. The mass was studied morphologically and immunohistochemically. Results. A 31-year-old woman underwent total thyroidectomy for papillary thyroid carcinoma. A mass suspected of recurrence was found 14 months later and caused dysphagia and dyspnea. An 18 F- fluorodeoxyglucose positron emission tomographic ( 18 F-FDG-PET) scan showed a lesion with high uptake; however, a fine-needle aspiration biopsy (FNAB) was inconsistent with recurrent cancer. The mass was resected and was composed of elongated spindle cells, with eosinophilic cytoplasm within a myxoid background. Immunohistochemical staining was strongly positive for vimentin, focally positive for smooth muscle actin, desmin, and p53, and negative for cytokeratin AE1/AE3, Cam5.2, epithelial membrane antigen (EMA), and anaplastic lymphoma kinase (ALK-1). Conclusion. Although postoperative spindle cell nodules are rare after thyroid surgery, it should be considered in the differential diagnosis for recurrent masses at the operative site. VC 2011 Wiley Periodicals, Inc. Head Neck 35: E13 E17, 2013 KEY WORDS: postoperative spindle cell nodule, thyroid neoplasms, thyroidectomy, neoplasm recurrence, local The incidence of thyroid cancer is rapidly increasing worldwide, and the number of thyroid biopsies and surgical procedures has correspondingly increased. 1 A postoperative spindle cell nodule is an exuberant tissue response associated with a previous biopsy or surgical trauma. Since the first description by Proppe et al, 2 postoperative spindle cell nodules have primarily been reported in the lower genitourinary tract. 2,3 There are also reports of postoperative spindle cell nodules arising in other areas such as the renal pelvis, 4 oral cavity, 5 skin, 6 and breast. 7,8 Baloch et al 9 reported in 10 patients spindle cell nodules in the thyroids after fine-needle aspiration biopsies (FNABs), ranging in size from 0.3 to 1.0 cm. 9 However, there are no reports of a postoperative spindle cell nodule after a thyroidectomy based on a review of the literature. Here we report a case of a postoperative spindle cell nodule arising in the thyroid bed after a total thyroidectomy, which mimicked an aggressive recurrence of thyroid cancer. CASE REPORT A 33-year-old Asian woman presented with a palpable neck mass and dysphagia during follow-up after initial *Corresponding author: J. S. Kim, Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea. js0507.kim@samsung.com treatment for thyroid cancer. She had undergone a total thyroidectomy and left modified radical neck dissection 2 years earlier. The pathology of the surgical specimen revealed a 2.5-cm classic-type papillary thyroid carcinoma in the left lobe, with perithyroidal soft tissue extension and lateral lymph node metastasis (left, levels 2 and 4) <1 cm in size. Postoperative remnant ablation with 150 millicuries (mci) radioiodine was performed and levo-thyroxine was administered to suppress thyroid-stimulating hormone (TSH) to levels < 0.05 microinternational units per milliliter (liu/ml). A follow-up 123 I diagnostic scan at 12 months postoperatively showed no thyroid remnants and stimulated thyroglobulin was not detected. However, a follow-up ultrasonography, performed 14 months postoperatively, showed a 1.5-cm hypoechoic round nodule in the left operative bed. Ultrasound-guided FNA showed aggregates of inflammatory cells and spindle cells (mostly fibroblasts), suggestive of benign postoperative findings. During follow-up, the size of the nodule, measured by ultrasonography, increased and the patient complained of progressive dysphagia and mild dyspnea upon exertion. An 18 F-fluorodeoxyglucose positron emission tomography ( 18 F-FDG-PET)/CT scan performed 18 months after total thyroidectomy showed a hypermetabolic mass (maximum standardized uptake value [SUVmax] ¼ 4.6) in the left thyroid bed, suggesting an aggressive recurrence of thyroid cancer (see Figure 1). However, repeated ultrasound-guided FNAB showed no evidence of malignancy. On neck CT and MRI, the HEAD & NECK DOI /HED JANUARY 2013 E13

2 KIM ET AL. FIGURE 1. Imaging studies of the postoperative spindle cell nodule after total thyroidectomy. (A) Maximum intensity projection and fused transaxial 18 F-fluorodeoxyglucose positron emission tomography ( 18 F-FDG-PET)/CT images showing a hypermetabolic lesion (maximum standardized uptake value [SUVmax] ¼ 4.6) in the left thyroid bed, which was suspicious for recurrent malignancy. (B) An axial CT scan at the level of the thyroid bed showing displacement of the trachea to the right side. (C) An MR image showing a mass with marked high-signal intensity on the T2-weighted image. Invasion into surrounding tissues was not observed. After administration of contrast, the lesion showed diffuse enhancement. mass was found to have displaced and compressed the trachea without clear invasion into the surrounding tissues (see Figure 1). Based on the growth of the mass with the associated symptoms and imaging findings, aggressive recurrence of thyroid cancer, such as anaplastic transformation, was suggested even though a repeat ultrasoundguided FNAB did not corroborate such a diagnosis. The patient subsequently underwent wide surgical removal of the mass, which required a manubriotomy to gain access to the entire lesion. The mass was densely adhered to the esophagus, trachea, left subclavian artery, and posterior cervical fascia. The left recurrent laryngeal nerve and left vertebral artery were sacrificed. On the final pathologic report, the specimen was diagnosed as a postoperative spindle cell nodule. A follow-up neck CT scan 12 months after surgery showed no evidence of residual or recurrent disease. Pathologic findings The surgical specimen was composed of soft and fleshy tissue, measuring mm. The mass had relatively ill-defined margins, and the cut section was fibrotic and gray-tan. On microscopy, the mass was found to be E14 HEAD & NECK DOI /HED JANUARY 2013

3 POSTOPERATIVE SPINDLE CELL NODULE AFTER THYROIDECTOMY FIGURE 2. Gross morphology and histomorphology of the postoperative spindle cell nodule. (A) The surgical specimen was a graytan tissue mass measuring mm and the cut section was homogeneous. (B) Proliferation of elongated spindle cells with eosinophilic cytoplasm within a myxoid background (hematoxylin-eosin stain; original magnification, 50) was observed (C, D). The lesion was highly vascularized and infiltrates of lymphocytes and neutrophils were noted (hematoxylin-eosin stain, original magnification, 400). composed of elongated spindle cells with eosinophilic cytoplasm within a myxoid background. The lesion was highly vascular, displaying delicate microvessels and infiltration of lymphocytes and neutrophils. The nuclei were large, but pleomorphism was minimal. Occasional mitotic figures (<1 2 mitoses per 10 high-power fields) were identified, although none was atypical. No necrotic areas were noted (see Figure 2). Immunostaining was performed on sections of a paraffin block with appropriate controls. Expression of vimentin was quite high and focal positivity for smooth muscle actin (SMA), desmin, and p53 was noted. Immunostaining for cytokeratin AE1/AE3, Cam5.2, epithelial membrane antigen (EMA), and anaplastic lymphoma kinase (ALK-1) was negative (see Figure 3). DISCUSSION A postoperative spindle cell nodule is an exuberant proliferation of spindle cells that occurs several weeks to months after instrumentation or trauma, including surgical procedures. Postoperative spindle cell nodules typically develop at the site of the incision. In 1984, Proppe et al 2 first coined the term "postoperative spindle cell nodule in a study involving a series of 8 patients with lower genital and urinary tract nodules appearing after surgical instrumentation. The male-to-female ratio was 1:1 and the patients ranged in age from 29 to 79 years. After surgical resection, 2 recurrences were noted but subsequent reexcision successfully removed the recurrent masses without further recurrence. Since the first description by HEAD & NECK DOI /HED JANUARY 2013 E15

4 KIM ET AL. FIGURE 3. Immunohistochemistry of the postoperative spindle cell nodule. Strong positive staining for vimentin and focal and weakly positive staining for smooth muscle actin (SMA), desmin, and p53 were noted. The mass was negative for epithelial membrane antigen (EMA) and anaplastic lymphoma kinase (ALK-1). Proppe et al, 2 postoperative spindle cell nodules have been reported in the lower genitourinary tract, 2,10 14 endometrium, 3 renal pelvis, 4 oral cavity, 5 skin, 6 and breast. 7,8 Baloch et al 9 reported spindle cell nodules of the thyroid, which appeared after thyroid FNAB (range, cm) in 10 patients. In our case, the postoperative spindle cell nodule was located in the thyroid bed after total thyroidectomy, and had a maximum diameter of 5.5 cm. Histologic examination of postoperative spindle cell nodules show elongated spindle cells with eosinophilic cytoplasm within a myxoid background. The nuclei are large but not hyperchromatic. Occasional mitotic figures are seen, although these are atypical. The lesions are usually vascular with infiltrates of inflammatory cells, such as lymphocytes and neutrophils, and are without necrosis. Sometimes histiocytes can be observed. These proliferative spindle cell nodules can mimic a sarcoma, but are clinically benign. These lesions have been reported to occur spontaneously or after trauma, including biopsies and surgical procedures. Lesions occurring spontaneously or after trauma have overlapping morphologies and are essentially indistinguishable; thus, the descriptive term pseudosarcomatous myofibroblastic proliferation has been proposed to signify this disease as a single entity by some authors. 10,11 For immunohistochemistry analysis, positivity for vimentin, SMA, and desmin are commonly reported, whereas the results for cytokeratin AE1/AE3 and Cam5.2 are equivocal. Some studies have shown that p53 immunostaining is useful for distinguishing postoperative spindle cell nodules from malignant neoplasms, because only focally reactive cells are noted in postoperative spindle cell nodules compared with strong and diffuse staining for p53, which characterizes malignant tumors. Negative results have been reported for EMA and ALK-1. 7,8,11,15,16 Our case showed strong immunostaining for vimentin and focal positivity for SMA, desmin, and p53. Staining for EMA and ALK-1 was negative. Thus, the overall immunostaining pattern in the specimen from our patient was in agreement with previous reports for postoperative spindle cell nodules. The question of whether postoperative spindle cell nodules are exuberant reactive processes or true neoplasm remains to be answered. History of prior trauma and microscopic findings of a myxoinflammatory background are evidence of underlying reactive processes, but there are emerging E16 HEAD & NECK DOI /HED JANUARY 2013

5 POSTOPERATIVE SPINDLE CELL NODULE AFTER THYROIDECTOMY immunohistochemical and molecular evidences that some of these lesions have characteristics of neoplasia. 15 The most common differential diagnoses for FNAB suggestive of spindle cell lesions in the thyroid bed include anaplastic transformation of recurrent thyroid carcinoma, medullary carcinoma, and sarcoma. However, postoperative spindle cell nodules should also be included in the differential diagnosis, especially when FNAB results do not demonstrate other features that are usually associated with malignancy. The treatment of choice for postoperative spindle cell nodules is surgical removal of the mass that causes symptoms. Considering that there is no evidence of recurrence or metastasis during follow-up periods from 9 months to 3 years from the literature review by Lott et al, 15 a less aggressive surgical approach for treating postoperative spindle cell nodules should be considered rather than wide aggressive resection, which is associated with morbid complications. 14 Until now, there have been no cases of postoperative spindle cell nodules reported to be treated by radiation therapy, either alone or in a postoperative adjuvant setting. In conclusion, we have described a patient with a postoperative spindle cell nodule that occurred in the thyroid bed after a thyroidectomy for treatment of thyroid cancer. Although postoperative spindle cell nodules are rare, they should be considered in the differential diagnosis of recurrent masses at the operative site after thyroid surgery in patients with thyroid cancer. REFERENCES 1. Davies L, Welch HG. Increasing incidence of thyroid cancer in the United States, J Am Med Assoc 2006;295: Proppe KH, Scully RE, Rosai J. Postoperative spindle cell nodules of genitourinary tract resembling sarcomas. A report of eight cases. Am J Surg Pathol 1984;8: Clement PB. Postoperative spindle-cell nodule of the endometrium. Arch Pathol Lab Med 1988;112: Jimenez Calvo J, Guarch Troyas R, Lozano Urunuela F, et al. Post-surgical spindle cell nodule in kidney pelvis [in Spanish]. Actas Urol Esp 2001; 25: Zellers RA, Bicket WJ, Parker MG. Posttraumatic spindle cell nodule of the buccal mucosa. Report of a case. Oral Surg Oral Med Oral Pathol 1992;74: Wick MR, Mills SE, Ritter JH, Lind AC. Postoperative/posttraumatic spindle cell nodule of the skin: the dermal analogue of nodular fasciitis. Am J Dermatopathol 1999;21: Gobbi H, Tse G, Page DL, Olson SJ, Jensen RA, Simpson JF. Reactive spindle cell nodules of the breast after core biopsy or fine-needle aspiration. Am J Clin Pathol 2000;113: Garijo MF, Val-Bernal JF, Vega A, Val D. Postoperative spindle cell nodule of the breast: pseudosarcomatous myofibroblastic proliferation following endo-surgery. Pathol Int 2008;58: Baloch ZW, Wu H, LiVolsi VA. Post-fine-needle aspiration spindle cell nodules of the thyroid (PSCNT). Am J Clin Pathol 1999;111: Hirsch MS, Dal Cin P, Fletcher CD. ALK expression in pseudosarcomatous myofibroblastic proliferations of the genitourinary tract. Histopathology 2006;48: Harik LR, Merino C, Coindre JM, Amin MB, Pedeutour F, Weiss SW. Pseudosarcomatous myofibroblastic proliferations of the bladder: a clinicopathologic study of 42 cases. Am J Surg Pathol 2006;30: Meister P. Spindle cell tumors and tumor-like changes of the prostate and surrounding tissue [in French]. Pathologe 1998;19: Young RH. Spindle cell lesions of the urinary bladder. Histol Histopathol 1990;5: Huang WL, Ro JY, Grignon DJ, Swanson D, Ordonez NG, Ayala AG. Postoperative spindle cell nodule of the prostate and bladder. J Urol 1990; 143: Lott S, Lopez-Beltran A, Maclennan GT, Montironi R, Cheng L. Soft tissue tumors of the urinary bladder, Part I: myofibroblastic proliferations, benign neoplasms, and tumors of uncertain malignant potential. Hum Pathol 2007;38: Iczkowski KA, Shanks JH, Gadaleanu V, et al. Inflammatory pseudotumor and sarcoma of urinary bladder: differential diagnosis and outcome in thirty-eight spindle cell neoplasms. Mod Pathol 2001;14: HEAD & NECK DOI /HED JANUARY 2013 E17