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

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