Ewing's sarcoma, primitive neuroectodermal tumour and neuroblastoma: morphological, immunohistochemical and electron microscopic study

Ewing's sarcoma [ES], primitive neuroectodermal tumour [PNET] and neuroblastoma [NB] are most commonly considered in the differential diagnosis of small blue round cell tumor of infancy and childhood. The differential diagnosis between these over- lapped tumours is of utmost importance for therapy and prognosis. The aim of this study was to assess the morphological, immunohistochemical and ultrastructural diagnostic features of these overlapping tumors. The study was done on 18 cases including eight cases of Ewing's sarcoma, ES [seven bone and one soft tissue], three cases of primitive neuroectodermal tumor [PNET] and seven cases of neuroblastoma, NB [all were primary tumors]. ES was diagnosed by its positivity for CD 99, the presence of glycogen either histochemically or by EM along with the classic morphology of ovoid cells lacking rosettes and spindle cell pattern. NB was diagnosed by its positivity for neuron specific enolase [NSE] and negativity for CD 99, the presence of neurites, neurosecretory granules and neuropils by EM along with the rosettes by light microscopy and the absence of glycogen both histochemically and by EM. PNET had some features of ES as the presence of glycogen and positivity for CD 99 as well as some features of NB as the positivity for NSE and the presence of neurosecretory granules and neurites as well as the occasional presence of rosettes by light microscopy

Histopathological and immunohistochemical study of Kikuchi-Fujimoto disease [Necrotizing Histiocytic Lymphadenitis]

In this work, 17 lymph node biopsies from 17 patients were studied. The cases showed a fragmentation of the lymph node [8/17], residual reactive germinal centers [11/17], focal paracortical necrosis [8/17] and large confluent areas of necrosis with disturbance of the normal architecture [9/17]. Karyorrhexis was a prominent feature [+++] in 10/17 cases, moderate [++] in 5/17 cases and mild [+] in 2/17 cases. The karyorrhectic process was intimately associated with coagulative necrosis. The present study showed that this disease has sufficient morphological and immunohistochemical characteristic features to allow for a precise histological diagnosis, in particular when these morphological features are seen within the right clinical context of a young female patient, a good general condition, localized cervical lymphadenopathy and fever of unknown origin

Langerhans cell histiocytosis: morphological, immunohistochemical and ultrastructural study

A total of 23 samples of 21 patients designated Langerhan's cell histiocytosis [LCH] or eosinophilic granuloma was collected for this study. Light microscopy showed that the picture of LCHs was a mixture of Langerhan's [LCs] and eosinophils in varying proportions along with the occasional giant cells of foreign body and Langerhan's giant cells, lymphocytes and neutrophils. The immunohistochemical study showed mostly negative staining for alpha-1-antitrypsin. Out of the 23 specimens, 19 were positive for S100. CD Ia was performed on all cases with 100% positivity. The macrophages were negative for CD Ia and S100, but were positive for alpha-1-antitrypsin. The staining for NSE was positive for 19 specimens, but it was nonspecific as the histiocytes showed also a positive staining. All the 21 cases studied by electron microscopy had the characteristic features of Langerhans' cell histiocytosis in the form of Birbeck granules along with the deeply cleaved or pseudo-multisegmented nuclei with finely dispersed, thinly marginated chromatin and inconspicuous nucleoli

melanotic melanoma of soft tissue [clear cell sarcoma]: immunohistochemical and electron microscopis comparative study with cutaneous melanoma

This study included 13 cases of amelanotic melanoma of soft tissue or clear cell sarcoma [CCS] compared with 24 cases of conventional malignant melanoma of skin. The immunohistochemistry of Melan A, HMB45, S100, EMA, CEA, vimentin and cytokeratin was done for both study groups. The malignant cells of CCS showed 100% positivity [13/13] cases for S100, vimentin and NSE; while, 8/13 and 7/13 cases were positive for HMB45 and Melan A, respectively. All cases were negative for CEA, EMA and cytokeratin [Pankeratin]. The conventional melanoma showed that all cases [24/24] were positive for S100, NSE and vimentin; while, Melan A positivity was seen in 19/23 cases and HMB45 positivity was found in 18/23 cases. All cases were negative for CEA and EMA, while 3/24 cases were positive for cytokeratin. The findings of electron microscopy observed in all cases of the amelanotic melanoma and conventional melanoma groups were the same. The most characteristic finding was the presence of premelanosomes which exhibited the typical lamellated striated or barrel-stone internal structure of premelanosomes