Case 17

Diagnostic ChallengePathology for Neurosurgery & Neurology

ResidentsDepartment of Pathology

University of Oklahoma Health Sciences Center,Oklahoma City, OK, U.S.A.

Case 17

History: A 12 year-old girl presented with a pineal mass and mild hydrocephalus. Other than headache, the patient does not have fever or other constitutional symptoms and the patient is immunocompetent. The followings are representative images.

Contributor: Kar-Ming Fung, M.D., Ph.D., karming-fung@ouhsc.edu Last updated: 3/9/2009

Cytologic Preparation Cytologic Preparation

Frozen Section Frozen Section

Paraffin Section Paraffin Section

CD68 (macrophages) CD3 (T-cells)

CD117 (c-kit) Placental alkaline phosphatase (PLAP)

What is your diagnosis?

Diagnosis: Pineal germinoma with extensive granulomatous changes.Discussion: • In contrast to Case 16, this cases is very challenging.• First, there are many macrophages (arrow) in the frozen

section cytologic preparation. Very few lymphocytes are present and there is no definitive large, atypical cells characteristic for germinomas.

• Second, the substantial amount of tissue is composed of granuloma as illustrated below (white arrows on the left, high magnification on the right).

CD117 PLAP

• On detailed high magnification examination of the submitted tissue, scant large atypical cells (arrows) are present within the granulomatous inflammatory tissue. Typically, biopsy specimen obtained by endoscopic biopsy from the pineal is minute and with crush artifacts. These artifacts are quite unavoidable but they make interpretation difficult.

• Immunohistochemistry demonstrated positive reactivity for both CD117 and PLAP. CD117 is usually more sensitive but it is not as specific for the diagnosis as PLAP or OCT 4, another antibody that could recognizes germinoma cells.

• The granulomatous reaction highly suggest infection. However, the clinical information is very helpful. It is hard to believe that an immunocompetent child of this age with an ongoing infection in the brain and without constitutional symptoms. In the end, one must recognize that germinoma, regardless their location, are prone to develop a variable amount of granulomatous changes. A small biopsy that contains mostly granulomatous changes can be mistaken as infectious rather than neoplastic. The consequence of this mistake can be serious.