Pleuropulmonary blastoma (PPB) is among the rarest pediatric malignancies [1,2]. It has been postulated that PPB may serve as a marker for predisposition of childhood neoplasms in other family members [3]. Various types of neoplasms have been reported either as second neoplasms in already affected PPB patients or as a first neoplasm in the relatives. To date, there have been four PPB patients (two were siblings) whose relative(s) had cystic nephroma [3][4][5][6]. Two other patients who had both PPB and renal cystic lesions were recently reported [3,7]. We describe here an additional patient with a PPB and a synchronous cystic renal tumor and briefly comment on the etiology and the clinical significance of this association.A Japanese boy aged 1 year 10 months was referred to our center because of abdominal distension. The patient was born to nonconsanguineous, healthy Japanese parents at 39 weeks of gestation. Personal and family (firstand second-degree relatives) histories were unremarkable. Imaging studies demonstrated a large multilocular tumor of the left kidney ( Fig. 1a) and a large, solid and cystic tumor in the left thoracic cavity (Fig. 1b). Diagnosis on imaging studies was a left renal tumor with a large lung/pleural metastasis. At first, the left renal tumor was biopsied; the sample revealed multilocular cysts lined by cuboidal epithelia and intervening fibrocollagenous tissue (Fig. 2a). There was no blastemal element or atypical cytologic features, so the histologic diagnosis was cystic nephroma (CN). The left intrathoracic tumor was biopsied subsequently; the sample revealed diffuse growth of spindle-shaped to oval atypical cells with hyperchromatic nuclei beneath the cystically dilated respiratory epithelia (Fig. 2b). The stroma was occasionally myxoid. Some tumor cells were rich in eosinophilic cytoplasm positive for desmin and myoglobin (Fig. 2c). Histologic diagnosis was PPB with rhabdomyoblastic differentiation. The patient underwent chemotherapy employing ifosfamide (isophosphamide), carboplatin, and etoposide. The left intrathoracic tumor decreased to less than half the original size and was resected 7 months after the onset. The tumor was completely necrotic and was replaced by collections of foamy histiocytes. The patient is alive and well without recurrence of metastasis 8 months after the onset. The left renal tumor has remained almost unchanged during the clinical course.
DISCUSSIONPleuropulmonary blastoma (PPB) usually occurs in patients under 5 years of age [1,2]. Recent studies have indicated that PPB may serve as a marker for predisposition of childhood neoplasms/dysplasias in other family members [3,4,7]. Although PPB is among the rarest pediatric malignancies, the incidence of familial disease is apparently high. Priest et al. [3] mentioned that an association between PPB and various types of other pediatric neoplasms/dysplasias was found in approximately 25% of the cases. Etiology of this newly recognized family cancer syndrome remains unknown.To date, there have been four cases of ...