Pineal Gland Lesions
A Cytopathologic Study of 20 Specimens
Anil V. Parwani, M.D., Ph.D.1
Blaire L. Baisden, M.D.2
Yener S. Erozan, M.D.1
Peter C. Burger, M.D.1
Syed Z. Ali, M.D.1
1Department of Pathology, The Johns Hopkins
Hospital, Baltimore, Maryland.
2Department of Pathology, Memorial Health Uni-
versity Medical Center, Savannah, Georgia.
Address for reprints: Syed Z. Ali, M.D., Department
of Pathology, The Johns Hopkins Hospital, 600
North Wolfe Street, Path 406, Baltimore, MD
21287; Fax: (410) 614-9556;
Received July 7, 2004; revision received Septem-
ber 7, 2004; accepted October 27, 2004.
BACKGROUND. Pineal gland lesions are rare, with only a few cytologic descriptions
occurring in the literature, according to the authors’ knowledge. The current article
describes the cytopathologic characteristics of 20 such lesions with discussion of
METHODS. Cytologic material was obtained either by fine-needle aspiration biopsy
(FNAB) under stearotactic radiologic guidance or by touch imprinting (TI) at the
time of frozen sectioning. The 20 specimens include pineoblastoma (five speci-
mens), pineocytoma (four specimens), astrocytoma (three specimens), germ cell
tumor (three specimens), meningioma (one specimen), epidermoid cyst (three
specimens), and pineal cyst (one specimen). Smears were stained with Diff-Quik
and with Papanicolaou and hematoxylin and eosin stains. In selected specimens,
immunoperoxidase (IPOX) stains were performed on cell block sections using
synaptophysin, neuron-specific enolase, placental alkaline phosphatase, glial
fibrillary acidic protein, leukocyte common antigen, cytokeratins, and human
chorionic gonadotropin antibodies.
RESULTS. Several cytomorphologic characteristics unique to each lesional category
with occasional overlapping features were observed. The unique features included
the following: small, hyperchromatic, round to oval cells with frequent rosetting
(pineocytoma), with a few specimens in addition showing hypercellularity, crowd-
ing, mitoses, and necrosis (pineoblastoma); pleomorphic round cells in a fibrillary
background (astrocytoma); large polygonal cells with prominent nucleoli and clear
cytoplasm (germ cell tumor); spindled fibroblastic cells (meningioma); anucleate
squames and mature squamous cells (epidermoid cyst); and small uniform polyg-
onal cells (pineal cyst). When necessary, IPOX studies supported the morphologic
CONCLUSIONS. FNAB and TI cytology were found to provide a rapid and reliable
diagnosis of pineal lesions. This is particularly important when dealing with
minute amounts of tissue material. Both techniques appeared to provide equally
good cytomorphology on smears. IPOX studies played an important complemen-
tary role in difficult cases when performed on cell blocks. Cancer (Cancer Cyto-
pathol) 2005;105:80–6. © 2005 American Cancer Society.
KEYWORDS: pineal gland, brain, fine-needle aspiration biopsy, touch imprint, cyto-
by the pia mater. The gland functions mainly as an endocrine organ
and produces the hormone melatonin. Levels of melatonin influence
the function of brain centers such as appetite and sleep. Microscop-
ically, the pineal gland has cords and clusters of epithelial-like cells
called pinealocytes, surrounded by a rich capillary network.
he pineal gland is a small body (weighing approximately 0.1 g) that
is attached to the posterior wall of the third ventricle and enclosed
© 2005 American Cancer Society
Published online 20 January 2005 in Wiley InterScience (www.interscience.wiley.com).
Pineal lesions are rare, most often occurring in
children and young adults.1The clinical presentation
of patients with pineal gland lesions includes head-
ache, paralysis of upward gaze, emesis, and seizures
caused by the increased pressure from the expansile
mass. Pineal lesions include nonneoplastic cysts and
benign or malignant tumors.2–6The most common
neoplasms are germ cell tumors, neoplasms of the
pineal parenchymal cells, and gliomas.3,7The germ
cell tumors include germinomas and teratomas, which
arise from embryonic remnants of germ cells. Tumors
of pinealocytes are the most common lesions of the
gland and include pineocytoma (PC; or pinealoma)
and pineoblastoma (PB). A pinealoma is comprised of
neoplastic nests of larger somewhat epithelial cells. A
PB is a small cell embryonal tumor (a primitive neu-
roectodermal tumor [PNET]).6An accurate diagnosis
has important clinical and therapeutic consider-
To our knowledge, there are only a handful of
reports of pineal gland lesions reported to date in the
cytopathology literature.13,14In the current study, we
analyzed the cytopathologic characteristics of 20 such
cases with elaboration on differential diagnosis.
MATERIALS AND METHODS
Cytologic material was obtained either by fine-needle
aspiration biopsy (FNAB) under stereotactic com-
puted tomography guidance or by touch imprinting
(TI) at the time of frozen sectioning. For the FNABs, a
dedicated neuroradiology suite was used by a team
comprising a neuroradiologist, a neurosurgeon, and a
cytopathologist. For the immediate on-site evaluation,
air-dried, Diff-Quik?–stained smears were used (Bax-
ter USA, Bloomington, IN). Wet-fixed (in 95% ethanol)
smears also were prepared and subsequently stained
with Papanicolaou stain. Needle rinses with balanced
salt solution were used to make paraffin cell blocks.
Four-micron sections were stained with hematoxylin
and eosin. In selected cases, additional 4-?m sections
were used for immunoperoxidase (IPOX) studies using
conventional methodology. The antibodies used in-
cluded synaptophysin, neuron-specific enolase (NSE),
placental alkaline phosphatase (PLAP), glial fibrillary
acidic protein (GFAP), leukocyte common antigen
(LCA), cytokeratins (AE1/AE3), and human chorionic
gonadotropin (HCG; Table 1).
Table 2 shows the clinicodemographic data for the
patients in the current study. There were 20 speci-
mens from 17 patients. The mean age of the patients
was 23 years (range, 1–60 years). There were nine
males and eight females (male-to-female ratio, 1.2:1).
The most common presenting complaints included
headache, nausea, emesis, ataxia, and decreased vi-
sual acuity. Radiographic studies most commonly dis-
closed a predominantly solid (occasionally cystic), hy-
podense or hyperdense mass in the region of the
pineal gland, often associated with microcalcifications
and either with or without surface ring enhancement.
Diagnostic entities included PB (five specimens), PC
(four specimens), astrocytoma (three specimens),
germ cell tumor (three specimens), meningioma (one
specimen), epidermoid cyst (EC; three specimens),
and pineal cyst (one specimen).
Antibodies Employed in Immunostaining
Placental alkaline phosphatase
Glial fibrillary acid protein
Common leukocyte antigen
Human chorionic gonadotrophin
aDako Corporation (Carpinteria, CA).
bChemicon (Temecula, CA).
Patient no.Diagnostic procedure
FNAB: fine-needle aspiration biopsy; TI: touch imprint.
Pineal Gland Lesions/Parwani et al.81
The pathologic features of the study specimens are
shown in Table 3.
All PB specimens displayed an aggressive clinicoradio-
logic presentation. For example, after an autopsy was
performed on one patient, the mesial surface of the
patient’s brain showed a large, extensively necrotic,
hemorrhagic tumor mass involving the ventricles and
extending well into the cerebellum (Fig. 1). Smears
from the PB specimen were hypercellular and de-
picted small, round “primitive-appearing” blue cells.
Although a significant proportion of the smears com-
prised single discohesive malignant cells, the tumor
showed a tendency to form intact tissue fragments
(Fig. 2). The cells in these fragments were tightly
crowded and overlapping. Rosette formations were
evident focally. The individual cells had round nuclei
and a barely discernible rim of pale cytoplasm. The
nuclei appeared extremely hyperchromatic with single
or multiple small nucleoli. Mitoses/karyorrhexis were
numerous. The adjacent cells in these fragments often
showed nuclear molding (Fig. 2, inset). Areas of ne-
crosis were readily identifiable. An interesting feature
observed in the cell block sections was the tight ag-
gregation of the small round blue cells around the
endothelial lining of small vessels reminiscent of peri-
theliomatous formations. IPOX stains performed in
two selected specimens revealed positivity for NSE
and synaptophysin and negativity for LCA.
Cellular smears from PC specimens showed numerous
single cells and small tissue fragments. The eye-catch-
ing low magnification appearance was a perivascular
placement of the neoplastic cells, resulting in tight
Diagnosis Cytomorphologic features
Pineoblastoma Small round blue primitive-appearing cells, occasional
pseudorosettes, nuclear molding,
mitoses/karyorrhexis, and necrosis. Neuronal
differentiation by IPOX studies.
Predominantly intermediate-size monomorphic cells,
bare nuclei, perivascular arrangement papillary-
like, well formed oval rosettes. Lack
mitoses/karyorrhexis. Neuronal differentiation by
Biphasic cell population comprising mature
lymphocytes (often with crushed artifact) and large
pleomorphic, polygonal cells with round nuclei,
prominent nucleoli, and clear or finely vacuolated
cytoplasm. IPOX studies are positive for PLAP, and
negative for cytokeratin and GFAP.
Hyperchromatic, pleomorphic small to intermediate-
size cells in a fibrillary background. Occasional fine
branching capillaries and gemistocytes. IPOX
studies are diffusely positive for GFAP. Pilocytic
subtype shows elongated nuclei, abundant well
formed cytoplasmic processes, and eosinophilic
granular bodies. May show Rosenthal fibers.
Whorls and syncytia of bland fibroblastic-type cells
with fusiform nuclei. Nuclear grooves and
Scantly cellular with reactive glial cells and few benign
polygonal parenchymal cells.
Abundant mature squamous cells in the absence of
any other cellular component. Granular debris. Cell
blocks may show intact cyst wall.
IPOX: immunoperoxidase; PLAP: placental alkaline phosphatase; GFAP: glial fibrillary acidic protein.
FIGURE 1. Pineoblastoma. Mesial surface of the brain depicting a large,
extensively necrotic tumor filling the ventricular spaces and involving the
FIGURE 2. Fine-needle aspiration biopsy specimen of a pineoblastoma.
Shown are cohesive fragments of small round primitive-appearing malignant
cells with crowded hyperchromatic nuclei. Inset: Nuclear molding and mitotic
figure (Papanicolaou stain, ? 400 and ? 600 [inset]).
82CANCER (CANCER CYTOPATHOLOGY) April 25, 2005 / Volume 105 / Number 2
branching “papillary-like” structures (Fig. 3). This type
of architecture was evident in 3 of the 4 (75%) PC
specimens. The neoplastic cells had intermediate-
sized, monomorphic, round nuclei with hypodense
chromatin and no nucleoli. Abundant naked tumor
cell nuclei were observed in the smear background,
resembling lymphocytes. Well formed rosettes were
readily identifiable (Fig. 4). In contrast to the PB spec-
imens, no mitotic figures were noted and tumor ne-
crosis was not evident. In none of the specimens were
IPOX stains needed for the diagnosis.
Germ cell tumor
All three germ cell tumor specimens in our series were
germinomas. The smears showed irregular fragments
of large pleomorphic cells. Numerous crushed cells
were observed in the smears, which corresponded to
the lymphocytic component of the neoplasm. The
neoplastic cells had polygonal shapes and relatively
abundant cytoplasm that was pale blue to clear and
finely vacuolated (Fig. 5). Nuclei were round and had
prominent nucleoli. Most cells displayed fragile, easily
disrupted cytoplasm, resulting in a significant popu-
lation of large naked nuclei (Fig. 5, inset). No glandular
formations were observed. The slide background was
distinctly granular, consistent with the glycogen-rich
material commonly observed in gonadal germinomas
as well. Cell block sections displayed the biphasic ap-
pearance of large pleomorphic malignant cells and
showed cytoplasmic staining for PLAP (Fig. 6, inset),
and were negative for HCG, GFAP, and cytokeratin
Anaplastic astrocytoma specimens displayed diffusely
cellular smears comprising small to intermediate-
sized neoplastic cells having round, oval, or irregular-
shaped nuclei, speckled chromatin with small nucle-
oli, and scant to no cytoplasm. The smears had a
characteristic fibrillary background. One specimen
had numerous gemistocytes. Although the tumor cells
showed significant pleomorphism, mitoses/karyor-
rhexis or necrosis was not identified. Both specimens
showed fine branching capillary vessels. However, en-
dothelial/microvascular proliferation was not ob-
served. Pilocytic astrocytoma specimens disclosed
more elongated, often pointed nuclei, well formed
cytoplasmic processes, and occasional eosinophilic
granular bodies. Rosenthal fibers were not observed.
FIGURE 3. Fine-needle aspiration biopsy specimen of a pineocytoma show-
ing neoplastic cells with monomorphic round nuclei demonstrating perivascular
aggregation. Numerous naked nuclei can be observed in the background
(Diff-Quik stain, ? 200 [left] and ? 400 [right]).
FIGURE 4. Pineocytoma showing a well formed tumor rosette. Note nuclei
with more open chromatin and lack of nucleoli (Papanicolaou stain, ? 400).
FIGURE 5. Fine-needle aspiration biopsy specimen of a geminoma. Shown
are large pleomorphic cells with abundant pale, clear, or finely vacuolated
cytoplasm. Note prominent nucleoli and crushed lymphocytes in the back-
ground. Inset: Large naked nuclei of the neoplastic germ cells (Diff-Quik stain,
Pineal Gland Lesions/Parwani et al.83
The sole specimen of meningioma showed elongated
fusiform cells and appeared more mesenchymal in its
morphology. Numerous cells depicted prominent in-
tracytoplasmic inclusions and occasional nuclear
EC specimens displayed abundant anucleate squames
and mature “superficial-type” squamous epithelial
cells in a granular cystic background. Rare lympho-
cytes were present. However, no other cell types were
observed. Cell block sections revealed portions of the
partially intact cell wall comprised of focally keratin-
izing squamous epithelium.
The single specimen of a pineal cyst showed an un-
characteristic appearance of hypocellular smears with
a scant amount of reactive fibrillar glial-type tissue
material. Rare aggregates of small, uniform polygonal
cells suggestive of pineal parenchyma were also ob-
FNABs and TIs often are performed to evaluate space-
occupying lesions of the brain with proven high accu-
racy. In one recent study, a pathologic diagnosis was
established based on cytologic interpretation in 75%
of biopsy specimens of central nervous system (CNS)
mass lesions without morbidity or mortality.15Our
own experience at Johns Hopkins with an as-yet un-
published study involving 318 consecutive brain FNAB
specimens in a 10-year period showed a diagnostic
sensitivity of 77% and a specificity of 97%. Other stud-
ies also have shown this technique to be diagnostically
effective in dealing with a variety of nonneoplastic and
neoplastic processes of the CNS.16–19TI is widely prac-
ticed as a useful alternative or adjunct to freezing the
tissue material for an intraoperative diagnosis. In our
experience, a properly prepared TI provides excellent
cytomorphology for an accurate and rapid pathologic
diagnosis and is devoid of the freezing artifact so com-
monly observed when processing minute brain tissue
biopsy specimens. In addition, we did not find a major
difference when interpreting FNAB and TI smears,
with the exception of more intact tumor architecture
in FNAB specimens.
The pineal gland is a small organ located in the
posterior wall of the third ventricle. Various pathologic
processes can involve the pineal gland including pi-
neal cysts and various types of benign and malignant
tumors.20Microscopically, the pineal gland is com-
prised of clusters and cords of large, epithelial-like
cells called pinealocytes, surrounded by a rich capil-
lary network. Tissue smears show that pinealocytes
have a delicate cytoplasm and clefted nuclei with
folded membranes and speckled “salt-and-pepper”
chromatin. Although pineal cysts are tumor-like le-
sions and not true neoplasms, they are occasionally
difficult to distinguish from PC and astrocytoma.
From a therapeutic aspect, a precise differential diag-
nosis is critical. In some cases, the radiographic ap-
pearance of a pineal lesion may be consistent with a
pineal cyst but the final pathologic diagnosis may be
different. Fleege et al.2reported a series of 19 patients
with clinically symptomatic pineal cysts with clinical
features including headache, diplopia, nausea and
emesis, papilledema, and seizures. The lesions ranged
from 0.8 to 3.0 cm. The radiographic appearance of
the benign pineal cysts was highly variable, making
them difficult to distinguish from other pineal-region
The most common tumors involving the pineal
region include pineal parenchymal tumors (PPT) and
germ cell tumors.3,4,10,13,20In a clinicopathologic study
by Kang et al.,2043 pineal-region tumors were de-
scribed including germinomas, PCs, and PBs.20PPTs
are divided into PCs and PBs. PCs are well differenti-
ated tumors with morphologic features similar to pi-
neal parenchymal cells. PBs are highly malignant neo-
plasms found in children and young adults that
disseminate widely, as is common with PNETs. A de-
finitive distinction between PB and other small round
cell tumors (e.g., medulloblastoma and cerebral
PNETs) is not possible based on cytomorphology
alone. Clinicoradiologic information is critical for an
accurate interpretation. Herrick and Rubinstein4de-
FIGURE 6. Fine-needle aspiration biopsy specimen of a germinoma. Shown
is a cell block section with the characteristic biphasic appearance of large
polygonal tumor cells admixed with lymphocytes. Inset: Diffuse cytoplasmic
staining with placental alkaline phosphatase (Papanicolaou stain, ? 400).
84 CANCER (CANCER CYTOPATHOLOGY) April 25, 2005 / Volume 105 / Number 2
scribed a series of 28 PPTs including PBs (n ? 11) and
PCs (n ? 7). Pure PBs and mixed PPTs with a pine-
oblastomatous component are the most common pi-
neal tumors, as was observed in a study by Schild et
al.8who described 30 patients (15 male and 15 female
patients) with PPT. Their series included PCs (n ? 9),
PPT with intermediate differentiation (n ? 4), mixed
PPT with both PC and PB components (n ? 2), and
PBs (n ? 15).
Germ cell tumors such as germinoma, teratoma,
embryonal carcinoma, yolk sac tumor, and choriocar-
cinoma are observed frequently in the pineal region,
either as mixed germ cell tumors or as a pure individ-
ual component. Knierim and Yamada12reported an
incidence of 20.4%, of a total of 49 solid and vascular
pineal tumors. Pineal germinoma may exhibit carci-
nomatous differentiation. Ng13described the cytologic
features of five intracranial germinomas. The smears
showed sheets of large tumor cells with delicate cyto-
plasm and prominent nucleoli mixed with mature
Pineal tumors may metastasize to other locations,
making the cytologic diagnosis more challenging.
Gindhart and Tsukahara21described a primary germi-
noma of the pineal region that metastasized to the
lungs and compared the findings with those from a
testicular seminoma metastatic to the CNS. The tumor
cells from both types of lesions were indistinguishable
from one another.21
The cytomorphology of pineal lesions is striking
and characteristic patterns may be observed. These
include small to intermediate-sized, hyperchromatic,
round to oval cells with frequent rosetting (PC) with a
few specimens showing hypercellularity and necrosis
(PB). Other cytologic features include pleomorphic
round cells in a fibrillary background (astrocytoma),
polygonal cells with prominent nucleoli and clear cy-
toplasm (germ cell tumor), benign keratinizing squa-
mous cells (epidermoid cyst), and spindled fibroblas-
tic cells (meningioma). These cytologic features
correlated well with histology on the cell block sec-
tions, as well as the subsequent histologic material.
Ancillary studies such as the use of IPOX are often
Recognition of the type of lesion is critical and
guides the appropriate clinical management of the
patient.10The therapeutic approach to pineal lesions
is dependent on the radiographic appearance of the
tumor, clinical presentation, age of the patient, and
the final pathologic diagnosis. The cytomorphologic
appearance of the lesion and an accurate diagnosis
therefore are critical to ensure the appropriate man-
agement of the patient. The management of pineal
cysts may be either aspiration or shunt placement.22
Pineal tumors, when correctly diagnosed, can be
treated appropriately and successfully.1For some pa-
tients, early surgery to achieve complete tumor re-
moval may be the best choice. Some pineal neoplasms
can be treated successfully with surgery alone. In
other patients, surgery followed by radiotherapy may
be indicated.9,10,20,23Prognosis is dependent on tumor
type, and obtaining a pathologic diagnosis makes it
possible to modify therapy according to tumor type
and, therefore, improve patient survival.1,8,10
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