Spontaneous malignant transformation of a supratentorial pilocytic astrocytoma

Abstract

Pilocytic astrocytoma (PA) is a circumscribed neoplasia considered as a grade I astrocytoma by the World Health Organization. Its most common location is the cerebellum and it develops during the first two decades of the life. Prognosis is mostly excellent if gross-total resection can be achieved, with 10-year survival rates of up to 80%. Anaplastic or malignant transformation (MT) can rarely occur and is usually related to previous radiation. Spontaneous MT has exceptionally been reported. Histological criteria for diagnosis of MT are unclear, so no consensus exists. We present an atypical case of MT of a frontal PA without previous radiotherapy in a 28 years old patient. Also, we review the literature about prognostic factors of PA and discuss histological features that are considered as anaplastic or malignant in the PA.

Heterogeneity of histopathological presentation of pilocytic astrocytoma – diagnostic pitfalls. A review

“…Only occasionally, tumours with brisk mitotic activity, necrosis and marked nuclear pleomorphism have been diagnosed as anaplastic PA [82]. It has been documented that anaplastic/malignant transformation of PA occurred most often in association with previous ionizing radiation [75] or surgery alone [88], whereas spontaneous malignant transformation was unique [10,72,90]. The majority of anaplastic cases have been described in adults [10,101].…”

Pilocytic astrocytoma with anaplastic features presenting good long-term clinical course after surgery alone: a case report

“…In most papers, histological features of anaplastic PAs were characterized by increased cellularity, multiple mitoses, pseudopalisading necrosis, and endothelial cell proliferation in addition to typical findings such as eosinophilic granular bodies and Rosenthal fibers [1,9,10,13,18,19]. Genetic alterations, such as BRAF, RAF1, and NF1 gene, which may be involved in the development of PAs have also been recently investigated by genomic studies [14].…”

“…The present case was, however, a primary case of anaplastic PA. The primary anaplastic PAs have ever been rarely reported [1,10,18]. Here, we report a rare and successful case of primary anaplastic PA with good long-term outcome despite of no adjuvant therapy.…”

“…PAs are classified by the World Health Organization (WHO) as grade I tumors, which typically have an excellent prognosis [15]. Proliferative activity is generally low with MIB-1 labeling index ranging from 0 to 3.9 % [10]. However, it was reported that some PAs show clinically aggressive features exceptionally [1, 3, 6, 9-11, 13, 18, 19].…”

“…However, it was reported that some PAs show clinically aggressive features exceptionally [1, 3, 6, 9-11, 13, 18, 19]. Although the predictive factors for PAs with aggressive features remain controversial, most papers reported that histological anaplasia was one of the comparatively reliable findings [5,10,12,13]. PAs with anaplastic features or anaplastic PAs were seen in 2 to 5 % of PA cases [18].…”