| Abstract|| |
Papillary tumor of pineal region (PTPR) is extremely rare and poses diagnostic challenge with other central nervous system tumors having papillary architecture. Immunohistochemistry is crucial for a definitive diagnosis of PTPR.
Keywords: Central nervous system tumors, immunohistochemistry, pineal region, Papillary tumor of pineal region
|How to cite this article:|
Dogra S, Gupta P, Malhotra P, Bhardwaj M. Papillary tumor in pineal region: Immunohistochemistry meeting the diagnostic challenge. Indian J Pathol Microbiol 2020;63:100-2
|How to cite this URL:|
Dogra S, Gupta P, Malhotra P, Bhardwaj M. Papillary tumor in pineal region: Immunohistochemistry meeting the diagnostic challenge. Indian J Pathol Microbiol [serial online] 2020 [cited 2020 Sep 21];63:100-2. Available from: http://www.ijpmonline.org/text.asp?2020/63/1/100/277363
| Case Report|| |
Papillary tumor of pineal region (PTPR) is extremely rare and represent less than 1% of all intracranial tumors in adults. Tumors arising around the pineal gland may display predominant papillary features and can lead to diagnostic dilemma.
A 30–year-old male presented with complaints of headache and fever on and off. Magnetic resonance imaging (MRI) brain revealed a large lobulated heterogeneous, solid-cystic, intra-axial mass of size 2.8 (AP) × 2.4 (ML) × 3.5 cm (CC) in the pineal region infiltrating or compressing the dorsal midbrain and extending from the level of splenium of corpus callosum till level of midpons in craniocaudal extent. Radiological diagnosis considered was of pineocytoma and pineal parenchymal tumor of intermediate differentiation. Modified lateral supraorbital craniotomy with excision of the mass was performed. Intraoperative squash smears were prepared. Squash cytology revealed highly cellular smears composed of tumor cells arranged in predominantly papillary pattern with complex ramifications, rosette like formation, pseudorosettes and many singly scattered [Figure 1]a. Cells were round to oval with plasmacytoid morphology having an eccentric nuclei, granular chromatin, inconspicuous nucleoli and abundant pale cytoplasm [Figure 1]b. Occasional mitosis were noted. However, no necrosis was seen.
|Figure 1:(a) Squash smear shows papillary fragments and many singly dispersed tumor cells (Papanicolaou, ×40). (b) Tumor cells with plasmacytoid morphology eccentric nucleus and granular chromatin (Giemsa, ×400). (c) Histological section shows tumor with predominant papillary architecture (Haematoxylin and Eosin, ×40). (d) Columnar tumor cells arranged in perivascular pseudorosette and true ependymal rosette (Haematoxylin and Eosin, ×400)|
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Considering the predominant papillary architecture of the tumor, the differential diagnosis considered were PTPR, papillary ependymoma, papillary meningioma, choroid plexus papillomas and metastatic deposits. However, in conjunction with the clinical and radiological details provided, a differential of PTPR and papillary ependymoma were given. Tumor tissue sent for histopathology revealed a cellular tumor with infiltration into adjacent glial tissue and arranged in papillae, sheets and pseudorosettes [Figure 1]c. The cells showed mild nuclear pleomorphism with round to oval nuclei, stippled chromatin and eosinophilic to clear cytoplasm [Figure 1]d. An immunohistochemical panel was applied. The tumor was positive for CD 56, NSE and Vimentin [Figure 2]a. It showed weak focal luminal positivity for EMA and focal strong positivity for GFAP [Figure 2]b and c]. Pan CK, CK7 and CK20 were negative. Ki 67 positivity was 8–10%. CK 18 was applied for differentiation between PTPR and papillary ependymoma and revealed focal strong positivity for CK 18 [Figure 2]d. Final diagnosis given was PTPR. Despite ventriculoperitoneal shunting, the patient's condition deteriorated rapidly and the patient succumbed to death.
|Figure 2:(a) Diffuse membranous positivity for CD56 (DAB, ×400). (b) EMA shows focal luminal positivity (DAB, ×400). (c) Focal strong positivity for GFAP (DAB, ×400). (d) Focal strong CK 18 positivity (DAB, ×400)|
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PTPR was first described by Jouvet et al. in a series of six tumors and was subsequently adapted in the WHO schema of classification. It was a newly recognized entity in the 2007 WHO classification of central nervous system tumors. Its incidence is not determined till date because of the rarity of this neoplasm. Similarly, histologic grading criteria remain to be identified (WHO Grade II or III).
On radiology PTPR are well circumscribed heterogeneous masses with solid and cystic areas and are usually diagnosed as pinoecytomas. MRI demonstrates T1 hyperintensity which is quite characteristic. Aqueductal obstruction with hydrocephalus is a frequent associated finding.,
Description of PTPR on squash cytology is scarce and the present case showed elaborate papillary configuration with numerous single plasmacytoid cells and rosette formation. Cytological features include high cellularity, true papillary configuration, and many singly scattered cells, presence of cytoplasmic vacuoles, and plasmocytoid cell morphology.
Central nervous system tumors exhibiting a papillary pattern can be difficult to classify on histomorphology alone and differential diagnosis with IHC should be considered for reaching a final diagnosis of PTPR [Table 1]. PTPR is believed to arise from ependymal cells of the subcommisural organ thus explaining papillary ependymoma as its closest differential. They share similar morphological and immunohistochemical profile except for CK 18.
|Table 1: Differential diagnosis of papillary tumors of central nervous system in the pineal region|
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There is presence of multilayered papillary fragments and pseudorosettes in PTPR as opposed to single layered well-formed papillae, seen in choroid plexus tumors. A thorough clinico-radiological evaluation is needed to rule out an occult primary. Another rare differential is papillary meningioma which can arise inside the ventricles. Lack of cytokeratin expression differentiates papillary meningioma from PTPR.
The clinical course and treatment of PTPR is not well delineated in literature due to the scarcity of the cases reported. At present, treatment for PTPR involves a multispecialty approach, i.e., combination of surgery and radiotherapy with or without chemotherapy is used. The 5-year estimates of overall and progression-free survival are 73% and 27%, respectively.
The present case highlights the spectrum of papillary tumors to be kept as differentials in a case presenting with a mass in pineal region with wide extension. Papillary ependymoma and PTPR share many morphological and immunohistochemical traits. Specific immunohistochemical staining for CK 18 remains the mainstay for diagnosis of PTPR.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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