Recent advances in diagnostic imaging and experience with
germinomas may allow for the differentiation of central nervous system
germinomas from other
tumors based on clinical information, without histological verification. We retrospectively analyzed clinically diagnosed
germinoma-like
tumors of the pineal and/or suprasellar regions. This was done to evaluate the efficacy of our strategy of defining
germinoma-compatible
tumors based on good responses to initial
chemotherapy. The responses to
chemotherapy and survival of 34 consecutive patients with
germinoma-like
tumors who underwent initial treatment from July 2001 to October 2010 were analyzed. The minimum apparent diffusion coefficient (minADC) value and
proton magnetic resonance spectroscopy (MRS) were evaluated in recent patients. Twelve patients with histologically verified
germinomas and 18 with
germinoma-compatible
tumors showed early logarithmic decreases in
tumor volume in response to initial
chemotherapy, typical low minADC values and typical MRS characteristics, including increased
choline/
creatine ratios, decreased N-acetylasparate/
creatine ratios, and large
lipid peaks. These patients had good progression-free survival. The other four patients, with histologically verified non-
germinomas, showed no response to
chemotherapy, and one patient with a
pineoblastoma showed a similar minADC value and MRS characteristics to those of patients with
germinomas. The response to initial
chemotherapy can be used to distinguish
germinoma-compatible
tumors from non-
germinoma in patients with
germinoma-like
tumors of the pineal and/or suprasellar regions. The evaluation of minADC and
proton MRS are useful for distinguishing
germinomas from other
tumors. However, a subset of non-
germinomas may show similar characteristics to
germinomas. The benefit of bypassing unnecessary surgical intervention can be achieved, at least in Asian populations with a high incidence of
germinomas.