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Correspondence

Intranodal palisaded myofibroblastoma: A case report and an update on etiopathogenesis and differential diagnosis

ABSTRACT Nandyala Intra-nodal palisaded myofibroblastoma (IPM) is a rare benign mesenchymal tumor. It presents as a slow growing, painless Hariharanadha nodular mass confined mostly to the inguinal area. Histologically, it shows palisading spindle cells, hemorrhages, hemosiderin laden Sarma, macrophages, and amianthoid fibers, almost totally replacing the lymph node. Recent genetic evidence supports viral etiology. A case Katepogu of IPM occurring in a 25-year-old woman is presented and the differential diagnosis of this lesion is discussed. IPM occurs between Sateesh Arora, 4th and 6th decade of life, male to female ratio is 2:1 and the inguinal region is the commonest location. Origin of this tumor is from Kalyanadurgam 1 myofibroblasts or smooth muscle fibers. Though benign, morphologically it can be confused with malignant tumors like Kaposi’s , Pujari Varalaxmi , and leiomyosarcoma. Prognosis is excellent and surgical excision is the only needed treatment. There are no reports of Departments of malignant transformation though an occasional case has recurred. Pathology, Rural Development Trust Hospital, Bathalapalle, KEY WORDS: Amianthoid fibers, intranodal, lymph node, myofibroblastoma 1Government Medical College, Anantapur, Andhra Pradesh, India

INTRODUCTION diagnosis of metastatic sarcoma in the groin was For correspondence: made. Fine needle aspiration cytology (FNAC) of Dr. N. Hariharanadha Intra-nodal palisaded myofibroblastoma (IPM) is a the swelling was reported as possible benign soft Sarma, rare benign mesenchymal tumor arising possibly tissue tumor. Department of Pathology, Rural from the myofibroblast or smooth muscle fibers Development Trust present in the lymph node. Until 1989 this tumor The swelling was excised for confirmatory Hospital, was diagnosed as intra-nodal schwannoma or diagnosis and further management. The patient Bathalapalle - 515 661, leiomyoma.[1] Weiss et al.[2] proposed the name was discharged without complications and is free Andhra Pradesh, India. palisaded myofibroblastoma. The synonyms for of the disease so far. E-mail: nandyalahari@ yahoo.com this lesion are intra-nodal hemorrhagic spindle cell tumor with amianthoid fibers[3] and solitary The specimen received was a well-circumscribed spindle cell tumor with myoid differentiation nodular greyish brown firm mass of size of the lymph node.[4] The term “INTRANODAL” 2 × 3 × 4 cm. Cut surface was greyish brown. was added afterwards to call this lesion as Histology of the representative areas revealed a “IPM.”[5] Its morphology can be confused with tumor replacing the lymph node almost totally. a variety of malignant mesenchymal tumors Remnant lymphnode was seen at the periphery emphasizing the importance of correct diagnosis [Figure 1]. The tumor consisted of bland spindle of this tumor. Possible viral etiology is gaining cells arranged in whorls or in fascicles. Vague ground. It behaves like a benign tumor and nuclear palisading resembling Antoni A areas were surgical excision is sufficient for treatment. seen at places. Small, stellate, round, or irregular There has been no malignant transformation or eosinophilic acellular fibrillary structures were metastasis by this tumor, though an occasional seen scattered throughout the tumor [Figure 2]. Access this article online case has recurred. Extensive areas of fresh and old hemorrhages with Website: www.cancerjournal.net hemosiderin laden macrophages were seen within DOI: 10.4103/0973-1482.113395 CASE REPORT the tumor [Figure 3]. Occasional normal mitoses PMID: *** were seen. Quick Response Code: A 25-year-old woman presented with a gradually increasing painless swelling in the left groin of 3 Immunohistochemistry revealed positivity years duration. Physical examination revealed a for smooth muscle actin (SMA) [Figure 4] and single, painless, firm, mobile mass of size 2 × 3 cm. vimentin [Figure 5] and negative for S-100 protein No other significant findings were noticed. Clinical and desmin [Figure 6]. Histological diagnosis of

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Sarma, et al.: Intranodal Palisased Myofibroblastoma

Figure 1: Low power view of the lesion showing remnant lymphnode Figure 2: High power view of the tumor showing fascicles of spindle- at the top and the tumor below [H and E, × 4] shaped cells with stellate or round collagenous areas-so called amianthoid fibers. Focal calcification of these fibers is noted [H and E, × 20]

Figure 3: High power view of the tumor showing focus of hemorrhage and hemosiderin laden macrophages [H and E, × 20] Figure 4: Medium power view of positive immunohistochemistry stain for smooth muscle actin × 10

Figure 5: Medium power view of positive immunohistochemistry stain Figure 6: Medium power view of negative immunohistochemistry stain for vimentin × 10 for desmin × 10

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Sarma, et al.: Intranodal Palisased Myofibroblastoma IPM was made because of the typical clinical presentation, It is suggested that viral oncogenesis might be involved morphology, and immunohistochemistry profile. in the development of these lesions and possibly cyclin D1 overexpression may independently influence the spindle cells DISCUSSION as growth factor.[5]

IPM is a rare benign mesenchymal tumor of the lymph node, Nature of amianthoid fibers has been intriguing. Studies possibly derived from myofibroblasts or smooth muscle indicates that the center of these fibers is composed of type I fibers.[1] Though inguinal lymph node is the most common collagen whereas the periphery is made up of Type III collagen. location, involvement of , submandibular and Electron microscopy also confirms that amianthoid fiber is cervical lymph nodes,[6] and retroperitoneum[7] have been a collagen fiber and not an amianthoid fiber. This fiber has reported. smaller width than amianthoid fiber ranging from 80 to 150 nm versus 280 to 1000 nm.[5] IPM as a disease entity was established in 1989. Before that this entity was considered as primary or secondary So far 70 cases are reported in the literature, 65 cases neurilemmoma, leiomyoma, or malignant Schwannoma of including our present case involved inguinal region, 4 cases the lymph node.[1] Weiss and collegues proposed the name submandibular region, and 1 case retroperitoneum. Inguinal palisaded myofibroblastoma. The term “INTRANODAL” was lymph nodes are preferably involved possibly because of added afterwards to call this “IPM.”[2,5] increased number of myofibroblasts secondary to increased drainage function.[2,5,9] IPM has been reported in ages between 25 and 78 years. There is only one case seen in an infant.[8] IPM presents as a solitary IPM has to be differentiated from benign lesions like leiomyoma, asymptomatic painless nodular mass in the inguinal region. intranodal schwannoma, inflammatory pseudotumor, and Men are more commonly affected than women. The tumor metastatic lesions in lymph node like , melanoma, is well capsulated, usually seen deep in the groin below the Kaposi’s sarcoma, and leiomyosarcoma. inguinal ligament and involves a single lymph node without infiltrating the overlying skin.[1] Leiomyoma shows typical morphology and IHC positive actin, desmin and vimentin, and negative human melanoma black Gross features include grey white tumor with multifocal [HMB]-45. Schwannoma will have typical Antoni A and B hemorrhagic areas. Microscopically, the tumor has a nodular areas. S-100 is positive and actin, desmin, and vimentin are configuration with fascicles of spindle cells. The nuclei may negative by IHC. Inflammatory pseudo-tumor differs by its display palisading pattern. Nuclear atypia is absent and inflammatory morphology which is not a feature of IPM. mitoses are rare. Metastatic or primary in the lymph node show The characteristic feature seen in all cases is the presence of features of sarcoma-like nuclear atypia and increased mitotic mats of eosinophilic material forming bands of stellate or activity. Melanoma can be excluded by negative HMB-45 circular profiles.[5] This material called as amianthoid fibers is and S-100 protein by IHC. Kaposi’s sarcoma shows typical considered to represent degenerated or crystalline collagen.[9] slit-like vascular spaces, extracellular eosinophilic bodies, Scattered foci of hemorrhages and extravasated red blood cells high mitoses, and nuclear pleomorphism. Amianthoid in between the spindle cells are seen. fibers are not a feature of Kaposi’s sarcoma. Positive CD34 and negative actin by IHC helps to differentiate Kaposi’s The histogenesis is still not completely understood. The cell sarcoma. of origin is most likely to be the myofibroblast or smooth muscle cell of the lymph node blood vessels.[2] Positive Diagnosis of IPM is important since potential confusion with staining for vimentin and actin and negative staining primary or metastatic mesenchymal in the lymph for desmin by immunohistochemistry (IHC) supports this nodes can be avoided. Since IPM mostly presents as inguinal notion. swelling, one should keep IPM in the FNAC diagnosis for inguinal swelling. Features like moderate spindle cell lesion Electron microscopy shows irregular contours of the nucleus without nuclear atypia, fibrillary stroma, and presence of and occasional intra-nuclear pseudoinclusions. Cytoplasm hemosiderin granules can favor IPM in FNAC. shows focal densities believed to be smooth muscle myofilaments. Better understanding of IPM will help in proper diagnosis and management because IPM is a benign lesion with very low or There is a proven association between Epstein–Barr virus and negligible rate of recurrence. We conclude with the emphasis human herpes virus 8.[10] In addition some cases of IPM have that IPM should be kept in mind for a swelling in the inguinal shown overexpression of cyclin D1.[5] lymph node.

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Sarma, et al.: Intranodal Palisased Myofibroblastoma REFERENCES histological spectrum. Histopathology 1990;16:287-93. 7. Sagar J, Vargiamidou A, Manikkapurath H. Intranodal palisaded 1. Iochim HL, Medeiros LJ. Spindle Cell Neoplasms of the Lymph Nodes. myofibroblastoma originating from retroperitoneum: An unusual Lymph Node Pathology. Philadelphia: JB Lippincott Company; 2008. origin. BMC Clin Pathol 2011;11:7. p. 571-3. 8. Rahimi S, Onetti Muda A, Faraggiana T. Multicentric intranodal 2. Weiss SW, Gnepp DR, Bratthauer GL. Palisaded myofibroblastoma. myofibroblastoma in an infant. Histopathology 1995;27:477-8. A benign mesenchymal tumor of lymph node. Am J Surg Pathol 9. Eyden BP, Harris M, Greywoode GI, Christensen L, Banerjee SS. 1989;13:341-6. Intranodal myofibroblastoma: Report of a case. Ultrastruct Pathol 3. Suster S, Rosai J. Intranodal hemorrhagic spindle-cell tumor with 1996;20:79-88. “amianthoid” fibers. Report of six cases of a distinctive mesenchymal 10. Kandemir NO, Barut F, Ekinci T, Karagülle C, Ozdamar SO. Intranodal of the inguinal region that simulates Kaposi’s sarcoma. palisaded myofibroblastoma (intranodal hemorrhagic spindle cell Am J Surg Pathol 1989;13:347-57. tumor with amianthoid fibers): A case report and literature review. 4. Lee JY, Abell E, Shevechik GJ. Solitary spindle cell tumor with Diagn Pathol 2010;5:12. myoid differentiation of the lymph node. Arch Pathol Lab Med 1989;113:547-50. 5. Nguyen T, Eltorky MA. Intranodal palisaded myofibroblastoma. Arch Cite this article as: Sarma NH, Arora KS, Varalaxmi KP. Intranodal palisaded myofibroblastoma: A case report and an update on etiopathogenesis and Pathol Lab Med 2007;131:306-10. differential diagnosis. J Can Res Ther 2013;9:295-8. 6. Fletcher CD, Stirling RW. Intranodal myofibroblastoma presenting in the submandibular region: Evidence of a broader clinical and Source of Support: Nil. Conflict of Interest: None declared.

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