Diagnosis and Discussion: Cystic Desmoplastic Medulloblastoma of Infancy
Figure 1. Cystic tumor (6 × 5 × 4.5 cm) in the right cerebellum. The largest cyst measures 3 cm in diameter and is filled with greenish fluid.
Figure 2. Undifferentiated areas composed of cells with small hyperchromatic nuclei and inconspicuous cytoplasm. The cells are arranged in cords and trabeculae (hematoxylin-eosin, original magnification ×280).
Figure 3. Marked desmoplasia with connective tissue encircling single cells or groups of cells (reticulin stain, original magnification ×550).
Figure 4. Scattered ganglion cells in a fibrotic background (hematoxylin-eosin, original magnification ×280).
At autopsy, the brain weighed 955 g. The right cerebellum contained a cystic tumor measuring 6 × 5 cm. Medulloblastomas are dense small cell tumors. They are heterogeneous but as a group are known for small hyperchromatic condensed nuclei and inconspicuous cytoplasm. There are several classifications: undifferentiated, neuroblastic differentiation, glial differentiation, mixed glial neuronal differentiation, and divergent differentiation.1 The desmoplastic variant of cerebellar medulloblastoma2 formerly identified by some workers as an arachnoidal cerebellar sarcoma3-5 is a superficial well-circumscribed form of medulloblastomas that predominantly occurs in young adults. Desmoplastic medulloblastoma has less nodularity compared with the other counterparts and a higher content of reticulin surrounding single cells or groups of cells. Abundance of connective tissue lends firmness to the tumor. The unique features of this case include (1) multiple cysts; (2) marked desmoplasia in a 1-year-old child; and (3) three types of clear-cut areas with abrupt transition: undifferentiated areas, mesenchymal areas with ganglion cells, and transition areas with follicular architecture (ie, pale islands).
Differential diagnosis of this tumor includes other cystic tumors and morphologically, desmoplastic tumors. Other differential diagnoses include (1) desmoplastic cerebral astrocytoma of infancy, (2) desmoplastic infantile ganglioglioma, (3) pilocytic astrocytoma of cerebellum, and (4) hemangioblastoma.
Desmoplastic cerebral astrocytoma of infancy6-8 is a superficially situated, supratentorial glioma. Grossly, the lesion appears as a large, firm, globular mass, densely adherent to the surface of the brain. A distinctive feature is the intense desmoplasia that imparts a fibrotic appearance. Scattered elongated glial cells, strongly positive for glial fibrillary acid protein, are seen. No ganglion cells are seen. Desmoplastic infantile ganglioglioma9,10 are supratentorial, superficially situated cystic tumors. Microscopically they show collagenous rich tissue of varying cellularity with an appearance of a neurofibroma. Ganglion cells are plump, small to medium sized, and mixed with glial cells or isolated within the desmoplastic tissue. The neuronal nature of these cells is suggested by their roundness, vesicular nuclei, variably prominent nucleoli, and Nissl substance. The spindle cells are strongly positive for glial fibrillary acid protein.
Pilocytic astrocytoma of the cerebellum can be seen as a mural nodule within a cyst. Despite gross circumscription, they permeate the surrounding tissue, particularly the white matter for some distance involving the overlying leptomeninges. They occur in the second decade of life. Microscopically stellate astrocytes in microcystic regions, Rosenthal fibers, and eosinophilic granular bodies are seen.
Hemangioblastomas, another cystic tumor of the cerebellum, are seen in adults and are dark red or yellow. A network of dilated vessels with variably lipidized stromal cells is seen microscopically. This tumor morphologically showed 3 types of clear-cut areas: undifferentiated areas, fibrotic areas with ganglion cells, and transition areas with follicular architecture (ie, pale islands) along with multiple cysts and marked desmoplasia.
Accepted for publication July 7, 2000.
Reprints: R. K. Vasishta, MD, FRCPath, Department of Histopathology, PGIMER, Chandigarh–160012, India.
1.Burger
PCGrehmann
PCBliestle
AKleihues
P Differentiation in the medulloblastoma: a histological and immunohistochemical study.
Acta Neuropathol. 1987;73115- 123
Google ScholarCrossref 2.Rubinstein
LJNorthfield
DWC The medulloblastoma and the so-called "arachnoidal cerebellar sarcoma": a critical re-examination of a nosological problem.
Brain. 1964;87379- 412
Google ScholarCrossref 3.Foester
OGagel
O Das umschriebene arachnoidal Sarcom des Kleinhirns.
Z Gesamte Neurol Psychiatr. 1939;164565- 580
Google ScholarCrossref 5.Ramsey
HJKernohan
JW Circumscribed sarcoma of the cerebellum: an electron microscopic study.
J Neuropathol Exp Neurol. 1964;23706- 718
Google ScholarCrossref 6.Taratulo
ALMonges
JLyeyk
PLeiguarda
R Superficial cerebral astrocytoma attached to dura: report of six cases in infants.
Cancer. 1984;542502- 2512
Google Scholar 7.de Chadarevian
JPPattisapu
JVFaerber
EN Desmoplastic cerebral astrocytoma of infancy: light microscopy, immunocytochemistry and ultrastructure.
Cancer. 1990;66173- 179
Google ScholarCrossref 8.Aydin
FGhatak
NRSalvant
JMuizelaar
P Desmoplastic cerebral astrocytoma of infancy: a case report with immunohistochemical, ultrastructural and proliferation studies.
Acta Neuropathol (Berl). 1993;86666- 670
Google ScholarCrossref 9.Ng
THKFung
CFMa
LT The pathological spectrum of desmoplastic infantile gangliogliomas.
Histopathology. 1990;16235- 241
Google ScholarCrossref 10.Vanderberg
SRMay
EERubinstein
LJ
et al. Desmoplastic supratentorial neuroepithelial tumors of infancy with divergent differentiation potential ("desmoplastic infantile gangliomas").
J Neurosurg. 1987;6658- 71
Google ScholarCrossref