title: Frequency of malignant solid tumors in children.
abstract: OBJECTIVE
  To find out the frequency of malignant solid tumors in children (< 15 years).
  
  
  METHODS
  All cases of pediatric malignant solid tumors which were diagnosed in the section of histopathology at the Aga Khan University Hospital, Karachi during the period of two years.
  
  
  METHODS
  These tumors were initially evaluated on H&E stained sections and special stains were also performed whenever indicated. The undifferentiated tumors were evaluated immunohistochemically by using a panel of antibodies on sections from routinely processed, formalin fixed, paraffin embedded tissue blocks.
  
  
  RESULTS
  Of two hundred and fifty three (253) consecutive cases of paediatric malignant solid tumors, lymphoma (26.1%) was the most common tumor followed by central nervous system tumors (16.6%), osteosarcoma (7.5%), rhabdomyosarcoma (6.7%), neuroblastoma (5.1%), Wilm's tumor (5.1%), Ewing's sarcoma (4.7%), retinoblastoma (4.7%), germ cell tumor (4.4%) and primitive neuroectodermal tumor (4%) in order of frequency. In seven cases (2.8%), the nature of lesion remained undetermined even after immunohistochemical staining. Rest of malignant tumors (12.3%) included the rare entities like synovial sarcoma, nasopharyngeal carcinoma, leiomyosarcoma, malignant schwannoma and thyroid carcinoma, etc.
  
  
  CONCLUSIONS
  Lymphoma was the most frequent Paediatric tumor. The frequency of childhood central nervous system tumors was quite high as compared to the other series from different regions of Pakistan.
authors.affiliation: Department of Pathology, Aga Khan University Hospital, Karachi.
authors.forename: S H
authors.initials: SH
authors.lastname: Shah
authors.forename: S
authors.initials: S
authors.lastname: Pervez
authors.forename: S H
authors.initials: SH
authors.lastname: Hassan
mesh_terms: D000293:Adolescent; D016543:Central Nervous System Neoplasms / Q000453:epidemiology; D002648:Child; D005260:Female; D006801:Humans; D008223:Lymphoma / Q000453:epidemiology; D008297:Male; D009369:Neoplasms / Q000453:epidemiology*; D010154:Pakistan / Q000453:epidemiology