University Journal of Pre and Para Clinical Sciences

ISSN 2455–2879 2017, Vol.3(4)

SOLITARY FIBROUS TUMOR OF LUNG MIMICKING AS LUNG METASTASIS IN A KNOWN CASE OF WILMS TUMOR.

SELVI

Department of Pathology, MADRAS MEDICAL COLLEGE AND GOVERNMENT GENERAL HOSPITAL

Abstract : Solitary fibrous tumor is the most common benign mesenchymal pleural neoplasm. It also affects mediastinum, lungs and other organs of any individual from young children to adults without sex predilection. Here we report a case of 4 years old child, a known case of treated Wilms tumor, presenting with a Solitary fibrous tumor of lung that was clinically mistaken for a lung metastasis. Ametachronous benign tumor occurring after a malignant tumor is a rare entity and whether it could bea part of any syndrome could not be established due to lack of molecular diagnostic studies. Keyword :Metachronous tumor Wilms tumor - Solitary fibrous tumor Lung. FIG 2 CT Image Axial View Mass Lesion R Lung

INTRODUCTION: As the patient is a known case of Wilms tumor operated one year back, a clinical diagnosis ofmetastatic Solitary Fibrous Tumor (SFT) is a rare benign neoplasm Wilms tumor was considered. Right thoracotomy was done and arising from pleura, mediastinum and the tumor was seen as a huge pleuro pulmonary mass and the lungs and virtually at any anatomic location. The tumor is most tumor was excised. The child gave a past history of being common in patients between 20 and 70years old. Hence we operated for Wilm’s tumor – Triphasic type, one year back, report a rare case of pulmonary SFT in 4year old child, who was followed by chemo and radiotherapy for the same ailment. The operated for Wilms tumor one year back. child was symptom free for a period of one year, after which the child presented with Right Lung lesion. CASE SUMMARY: A 4year old male child presented with breathlessness since GROSS: 4months.Chest CT picture revealed masslesion Rt lung [FIG1 & Excised Right lung mass measured 9x9x4 cm. External surface FIG 2]. was nodular and smooth [FIG 3]. Cut surface showed solid, grey-tan areas with focal whorled pattern [FIG 4]. Focal yellow- ish and

FIG 1 CT image - Coronal View shows Rt Lung mass Lesion FIG 3 External Surface - Nodular

An Initiative of The Tamil Nadu Dr. M.G.R. Medical University University Journal of Pre and Para Clinical Sciences

IMMUNOHISTOCHEMISTRY: The tumor was found to be positive for CD 34 [FIG 8 &FIG 9] and negative for CD 99 [FIG 11]& polyclonal CK [FIG 10]. With the above features a histological diagnosis of Solitary Fibrous Tumorwas made.

FIG 4 Cut Surface - Grey tan with whorled pattern

MICROSCOPY:

Histological examination showed a Circumscribed lesion [FIG 5] composed of sheets of plump spindle shaped cells with bland FIG 8: IHC – Tumor cells positive for CD34 X 10 nuclei [FIG 7] arranged in small fascicles, whorled [FIG 6] and in FIG 9: IHC - CD34 Positive cells X40 pattern less pattern, separated by abundant collagen fibers.

FIG 5 Circumscribed margin H&EX10 FIG 6 Spindle cells in whorled pattern H&EX10

FIG 7 Bland Nuclei H&EX40

An Initiative of The Tamil Nadu Dr. M.G.R. Medical University University Journal of Pre and Para Clinical Sciences

DISCUSSION: review of 360 cases in the literature. Cancer 1981; 47:2678– Solitary fibrous tumors represent 5% of all pleural 2689. neoplasms. Although initially thought to be of mesothelial origin, the tumor is now believed to originate 5 De Saint Aubain Somer- in the sub pleural nonmesothelial mesenchyme and indeed tumors hausen N, Rubin BP, Fletcher CD: Myxoid solitary fibrous with similar morphological features and immunophenotype occur tumor: a study of seven cases with emphasis on at several extra thoraciclocations such as lungs, orbit, mediastinu differentia diagnosis. Mod Pathol 1999; 12:463-471. m, liver, meninges,paranasal sinuses, peritoneum, salivary gland, r enal and urogenital tract. Intrapulmonary SFT are much less com 6 van de Rijn M, Lombard CM, Rouse RV: Expression of mon than their pleural counterparts.[1,2] Cystic degeneration is very CD34 by solitary fibrous tumors of the pleura, mediastinum, unusual, but solitary fibrous tumor can present as a mural nodule and lung. Am J Surg Pathol 1994; 18:814-820. within a large pleural-lined cyst. It may be found attached to the visceral pleura (80%) or parietal pleura, within an interlobar fissure, or sometimes within the lung parenchyma without a pleural connection.[3] Furthermore, although these tumors were described in all age groups from 5–87 years,[4] they are rarely seen inpatients less than 10 years of age. CT or MRI, or both, usually show a well-delimited tumor with smooth contours. Surgery is curative. Grossly, the tumors are well circumscribed, nonencapsulated, firm, white masses measuring less than 8cm. Foci of hemorrhage and myxoid change is often seen. Microscopically, bland lump spindle shaped cells are arranged in patternless pattern and surround branching blood vessels of the type associated with the hemangiopericytoma. Hemangiopericytoma-like areas are frequent, and some tumors have prominent myxoid features[5] Tumor cells are immunoreactive with CD34,[6] but a subset of tumors also shows reactivity for SMA, BCL2 and EMA and even focal positivity for desmin, cytokeratin and S100. It needs to be differentiated from other Spindle cell neoplasm such as Sclerosing hemangioma– atumor like,well-defined nonencapsu- lated mass arising in the periphery of lung. Microscopically tumor cells are cuboidal and arranged in papillary fashion with small spaces scattered in sclerosed areas.

Fibrous histiocytoma–A benign tumor derived from fibroblastic mesenchymal cells. More cellular with spindle cells arranged in storiform pattern and are seen in association with foamy macro- phages.

Hemangiopericytoma –.By current perception, both hemangiopericytoma & solitary fibrous tumor are considered to be different spectrums of a same lesion. 4.Monophasic synovial sarcoma– a malignant Spindle cell tumor with high degree of cellularity arranged in herring bone pattern. Tumor cells are posi- tive for CK, EMA and CD99.

CONCLUSION: The case under discussion is unique in two ways. One is that it occurred in a child, a rare age group for SFT. Second it occurred as a metachronous benign neoplasm, following Wilms tumor, a malignant tumor of kidney.

REFERENCES: 1.Patsios D, Hwang DM, Chung TB. Intraparenchymalsolitary fibrous tumor of the lung: an uncommon cause of a pulmonary nodule. J Thorac Imaging2006; 21:50 -53

2 Auero TX, McGary SA, Campbell DB et al. Intrapulmonary benign brous tumor of the pleura. J ThoracCardiovascSurg 1995; 110:549–551.

3 Yousem SA, Flynn SD: Intrapulmonary localized fibrous tumor. Intraparenchymal so-called localized fibrous mesothelioma. Am J Clin Pathol 1988; 89:365-369.

4 Briselli M, Mark EJ, Dickersin R. Solitary brous tumors of the pleura: eight new cases and

An Initiative of The Tamil Nadu Dr. M.G.R. Medical University University Journal of Pre and Para Clinical Sciences