| Abstract|| |
Extrarenal rhabdoid tumor (ERRT) is a rare, aggressive tumor with extremely poor prognosis. We report a case of ERRT with intraspinal extension in a 1.5-year-old child diagnosed by fine needle aspiration cytology (FNAC) and immunohistochemistry. The child presented with a right lumbar region lump of two months duration. Ultrasound guided FNAC was performed and cell block was prepared. Smears were highly cellular and showed a dispersed population of large round cells having abundant pale eosinophillic cytoplasm, centrally to eccentrically placed nucleus with large prominent nucleoli. Immunohistochemistry was carried out on cell block which was positive for epithelial membrane antigen EMA and Vimentin. It was negative for leucocyte common antigen [LCA], wilms tumor 1, WT1, desmin and neuron specific enolaseNSE, thus ruling out other tumors like lymphoma, Wilms tumor, rhabdomyosarcoma, and neuroblastoma. A final diagnosis of ERRT was given. ERRT is an extremely rare tumor of retroperitoneal area; it should be included in the differential diagnosis of malignant round cell tumor in children. Cell block in this case is mandatory for putting up the panel of immunohistochemistry which can clinch the diagnosis of rhabdoid tumor and treatment can be started as early as possible.
Keywords: Extrarenal, immunohistochemistry, needle biopsy, rhabdoid, tumor
|How to cite this article:|
Jain M, Harbhajanka A, Choudhary S R. Cytomorphology and immunohistochemistry of extrarenal rhabdoid tumor: A case report with review of literature. Indian J Pathol Microbiol 2011;54:819-21
|How to cite this URL:|
Jain M, Harbhajanka A, Choudhary S R. Cytomorphology and immunohistochemistry of extrarenal rhabdoid tumor: A case report with review of literature. Indian J Pathol Microbiol [serial online] 2011 [cited 2014 Sep 19];54:819-21. Available from: http://www.ijpmonline.org/text.asp?2011/54/4/819/91534
| Introduction|| |
Extrarenal rhabdoid tumor (ERRT) is a rare, aggressive tumor with extremely poor prognosis. The incidence of ERRT was reported as 0.15 per million children <15 years.  The central nervous system is the most frequent site of ERRT; however, it is reported in various sites of body.  Fine needle aspiration cytology (FNAC) is a highly effective technique for diagnosing pediatric tumors. There are very few case reports on cytological features of ERRT. , The histogenesis is uncertain; and on immunohistochemistry, it shows common mesenchymal and epithelial differentiation.  It is difficult to diagnose because of its varied morphological features, but it has to be distinguished from other round cell tumors like extra-renal Wilms' tumor (EWT), embryonal rhabdomyosarcoma, neuroblastoma, desmoplastic round cell tumor, malignant lymphoma, and melanoma as it needs intensive chemotherapy. We report a case of ERRT with intraspinal extension in a 1.5year-old child diagnosed by FNAC and immunohistochemistry was done on cell block.
| Case Report|| |
A one and half year old female presented with complaints of fever and failure to thrive for two months. On examination, abdominal lump was noted in right lumbar region. On computed tomography (CT) scan, a large heteroechoic mass measuring 12 × 8 × 7 cm displacing right kidney inferiorly which is normal and infiltrating into right posterolateral lower thoracic wall with intraspinal extension at T9, 10, 11 levels suggestive of neuroblastoma [Figure 1]. Ultrasound guided FNAC was performed using 22-gauge needle. Smears were stained with Giemsa and Papinacolaou stain. Cell block was prepared for immunohistochemistry.
|Figure 1: Large heteroechoic mass meas. 12 × 8 × 7 cm displacing right kidney inferiorly and infiltrating into right posterolateral lower thoracic wall with intraspinal extension at T9, 10, 11 levels|
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Smears were highly cellular showing predominantly large round to oval cells, having abundant pale eosinophillic to clear cytoplasm, central to eccentric large nucleus with very prominent nucleoli. These were seen isolated in small clusters and around blood vessels. On Giemsa stain, many cells showed eosinophillic inclusions with eccentrically placed nucleus [Figure 1]a. Similar pale grey colored inclusions were seen on Papinacolaou stain as well [Figure 1]b. Background showed dense myxoid background with few intermixed eosinophils and plasma cells. No rosettes or lymphoglandular bodies were seen. Possibility of rhabdoid tumor was suggested.
It showed isolated cells and small clusters around blood vessels with similar morphology as described above [Figure 2]c and d.
|Figure 2: (a) Highly cellular smears showing round to oval cells with abundant pale eosinophillic to clear cytoplasm and eosinophillic cytoplasmic inclusion (arrow) and central to eccentric large nucleus (Giemsa, ×1000); (b) Papinacolaou stained smears show pale grey colored cytoplasmic inclusions and prominent nucleoli (Papinacolaou, ×1000); (c) Cell block shows isolated cells and small clusters around blood vessels (hematoxylin and eosin, ×1000); (d) Cell block shows prominent eosinophillic cytoplasmic inclusion (arrow and inset)|
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Immunohistochemistry for EMA and Vimentin was positive. It was focal positive for cluster of differentiation (CD99) and cytokeratin CK [Figure 3].
Immunohistochemistry was negative for LCA, WT1, desmin, and NSE excluding lymphoma Wilms' tumor rhabdomyosarcoma and neuroblastoma. Final diagnosis of ERRT was given. On follow-up, patient died within a month of chemotherapy.
|Figure 3: Immunohistochemistry on cell block: (a) CD99; (b) CK; (c) EMA; (d) Vimentin (IHC, ×400)|
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| Discussion|| |
Rhabdoid tumor of kidney was first described by Beckwith and Palmer  as a sarcomatous variant of Wilms' tumor in 1978. Haas et al. in 1981 classified it as separate tumor. Malignant rhabdoid tumor (MRT) was subsequently reported in various sites like central nervous system, esophagus, stomach, small intestine, colon, liver, bladder, uterus, vulva, ovary, and soft tissues etc  and termed ERRT. The characteristic cytological features of MRT are non cohesive single cells, clusters or sheets of large tumor cells with abundant glassy eosinophillic cytoplasm, eccentric nuclei, prominent nucleoli, and intracytoplasmic inclusions in a background of necrosis, and high mitotic rate. FNAC of ERRT from retroperitoneal soft tissue has been seldom reported. There are only few reports on cytological features of extrarenal rhabdoid tumor [Table 1].
|Table 1: Previous case reports on fi ne needle aspiration cytology of Extrarenal rhabdoid tumor|
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Because of its varied morphological features, distinction from extra-renal Wilms' tumor (EWT), embryonal rhabdomyosarcoma, neuroblastoma (NB), desmoplastic round cell tumor malignant lymphoma, and melanoma is essential for therapeutic purposes.
EWT can be differentiated from MRT by the presence of dissociated small round blastemal cells with scanty cytoplasm and small nucleoli, epithelial cell groups with tubular or glomeruloid differentiation, and spindle stromal cells with elongated nuclei and are WT1 positive which was not seen in our case.
Rhabdomyosarcoma show characteristic cytological features of marked anisocytosis compared to MRT with elongated, strap- shaped, ribbon-like, or triangular myoblast type cells with cytoplasmic vacuolation in a blue-gray background and are desmin positive. These features were not present in our case.
Neuroblastoma (NB) on cytology shows characteristic rosettes formed by small round cells with long cytoplasmic extensions with central eosinophilic fibrillar material with NSE positivity. These features were not seen in our case.
Desmoplastic small round cell tumor (DSRCT) on cytology show cells with inconspicuous or absent nucleoli and frequent nuclear molding. Cytoplasm is usually less abundant and contains occasional vacuoles. Metachromatic stroma and occasional pseudorossetes in DRTC may also help in the differential diagnosis.
Malignant lymphoma shows mainly dispersed cells lying singly and not in clusters and background show lymphoglandular bodies which are absent in MRT aspirates. Moreover, lymphomas are LCA positive which was also negative in our case.
MRT can mimic melanoma in which prominent large nucleoli are seen. Intranuclear inclusions, cytoplasmic melanin pigment, and positivity for HMB45 are diagnostic of melanoma. These findings were not found in our case.
ERMRT is an aggressive tumor. This case also had very poor prognosis consistent with previous reports. ERRT is an extremely rare tumor of retroperitoneal area; it should be included in the differential diagnosis of malignant round cell tumor in children. Cell block in this case is mandatory for putting up the panel of immunohistochemistry which can clinch the diagnosis of rhabdoid tumor and treatment can be started as early as possible. Molecular analysis also plays an important role in establishing the diagnosis on FNAC specimen, but because of financial constraints, it is not possible in all the cases. ,,
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LHMC, Department of Pathology, C.P. Delhi
[Figure 1], [Figure 2], [Figure 3]