Calcifying nested stromal epithelial tumor of the liver - an unusual tumor of uncertain histogenesis

RK Ghodke, PA Sathe, BM Kandalkar 
 Department of Pathology, Seth G. S. Medical College, Mumbai, Maharashtra, India

Correspondence Address:
R K Ghodke
Department of Pathology, Seth G. S. Medical College, Mumbai, Maharashtra
India

Full Text

Sir,

Calcifying nested stromal-epithelial tumor (CNSET) is a unique tumor of uncertain histogenesis. The first case was described in 2001 in the Armed Forces Fascicle and subsequently less than 35 cases have been published inliterature. [1] Various terminologies have been used to describe this entity, however, "calcifying nested stromal-epithelial tumor" proposed by Makhlouf et al., incorporates all the features. [2]

We present a case of a nine-year-old boy, second of two siblings, born out of non-consanguineous marriage, without any significant family or past history of illness or tumor. He came with abdominal pain, fever, jaundice, weight loss and anorexia for two months. Routine investigations including liver function tests were normal. Computed tomography showed a liver mass diagnosed on biopsies on two occasions as hepatoblastoma and hamartoma respectively. Segmental hepatectomy specimen showed a well-circumscribed, firm to hard, white tumor measuring 5x5x5 centimeters [Figure 1] Histopathology showed a tumor with basophilic, short, spindle cells with distinct borders, scanty cytoplasm and stippled, vesicular nuclei, in a nested pattern. The desmoplastic stroma showed proliferating bile ductules. Psammoma-like calcification was also seen. Necrosis and mitoses were absent [Figure 2]. A diagnosis of CNSET was given. On immunohistochemistry, tumor cells were strongly positive for Wilms' tumor 1(WT1)), focally positive for Pan-cytokeratin and negative for chromogranin, desmin, Mic2 and neuron-specific enolase (NSE) antigens. Reverse transcriptase- Polymerase chain reaction (RT-PCR) analysis did not show (Ewing-sarcoma protien) EWS/WT1 translocation.{Figure 1}{Figure 2}

Literature review showed that the tumor occurred more commonly in females in the age group of two to 14 years and the size varied from two to 20 centimeters. [1],[2],[3] Associations have been described with Cushing syndrome, Wilms tumor and Beckwith-Wiedemann syndrome. [1],[4] Our case was a nine-year old boy with a tumor of 5 centimeters and had no syndromic association.

Mixed epithelial and mesenchymal hepatoblastoma may be difficult to differentiate when it has bone or calcification, but differentiation is essential as therapy is different. [2] A biopsy including only proliferating bile ductules may be misinterpreted as hamartoma, as seen in our case. Desmoplastic small round cell tumor (DSRCT) can be ruled out due to absence of necrosis, mitotic figures and presence of calcification. [4]

Immunohistochemically, all cases of CNSET are positive for WT1, also seen in our case, but its role as a diagnostic marker is not known. WT1 positivity, negativity for desmin and absent EWS/WT1 translocation differentiates it from DSRCT. [2]

CNSET is considered a benign tumor, however, stray cases of recurrence and lymph nodal metastasis have been reported, suggesting low malignant potential. [3],[4],[5] Thus it has an uncertain behavioral pattern. Our patient is doing well one year postoperatively.

Though a handful cases of CNSET have been reported, the exact histogenesis and the behavioral pattern is not very well known. More cases need to be studied to determine the biologic behavior and unify terminologies and hence the need to publish.

 Acknowledgment

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