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Background:The differentiation of extramedullary myelogenous leukemia/granulocytic sarcoma (GS) from malignant lymphoma can sometimes be difficult. In the current study, we explored the value of CD34, myeloperoxidase and nonspecific esterase (Leder) stains in differentiating GS from lymphomas. Materials and Methods: Fifteen cases of phenotypically confirmed GS were stained for CD34, myeloperoxidase and Leder stains. The same stains were performed in 16 malignant lymphomas as controls. The GS cases were also immunostained for CD3 and CD20 to detect the incidence of aberrant T and B lymphocyte expression. Results: CD34 was expressed in 7 of the 15 cases of GS (46%). Myeloperoxidase was expressed in 10 of the 15 cases (66%), and Leder stain was positive in 9 cases (60%). All 15 cases had expression of at least one marker; 8 cases had expression of two markers and one case had expression of all 3 markers. None of the lymphomas showed expression of any of the three markers. Five cases (35%) of GS showed T cell antigen expression and 2 (14%) showed B cell antigen expression. Conclusion: Our findings suggest that in cases of GS, the use of the combination of CD34, myeloperoxidase and Leder stains can help reach a definitive diagnosis, especially if lymphoma is difficult to exclude. Expression of B and T cell antigens in such lesions should not rule out the diagnosis of GS.

Intestinal spirochetosis is generally considered a saprophytic infestation of the large bowel mucosa. Since this term was introduced in 1967, 1 there have been many reports of colorectal spirochetosis, including one from Saudi Arabia.2 Appendicealspirochetosis, however, is less commonly reported. A Medline search of the English language literature yielded only four reports of appendicealspirochetosis describing 85 cases before 2001. 3-6The reported incidence of spirochetosis in otherwise normal appendices has varied between 3.7% 6 and 12.3%. 4 We reviewed 598 consecutive appendectomy specimens with intact surface epithelium and found only two cases of spirochetosis. Spirochetosis is generally considered a harmless infestation colonizing the large bowel epithelium.3 Ultrastructural studies have shown variable results regarding the invasiveness of spirochetes.7-10 The purpose of this paper is to present our light microscopic and ultrastructuralobservations in the first two cases of appendicealspirochetosis from Saudi Arabia. Patients and MethodsThis report is based on a retrospective study of 679 appendectomy specimens received during a period of two years in the Department of Histopathology at the Armed Forces Hospital, Riyadh, Saudi Arabia. Eighty-one cases that lacked an intact surface epithelium were excluded from the study. These included 65 cases of acute appendicitis and 16 cases of appendiceal fibrosis. For light microscopy, cross sections of the base and middle of an appendix and a longitudinal section of the tip were processed for paraffin embedding. Sections were routinely cut and stained with haematoxylin and eosin (H&E) stain. Sections with epithelial surfaces suspicious of spirochetal colonization on H&E were also stained with Warthin-Starry (WS) stain. Electron microscopy was carried out on one of the two appendices showing spirochetosis. One-millimeter slices were taken from the remaining formalin-fixed tissue. These were post-fixed in 3% glutaraldehyde and processed for electron microscopy using standard techniques. ResultsOf 598 appendectomy specimens with intact surface epithelium, a diagnosis of acute appendicitis was made in 473 appendices (79%) followed by 22 parasitic infestations (4%) and 6 tumors (1%) ( Table 1). Ninety-seven appendices (16%) were histologically normal except for neuromatous hyperplasia in 3 cases and spirochetosis in two cases. The incidence of spirochetosis was 0.3% of all the appendices and 2% of the normal looking ones. Both patients with spirochetosis were male, aged 18 and 25 years. Both presented with abdominal pain and were diagnosed with acute appendicitis on clinical grounds. Although their HIV status was not known, both appeared immunocompetent and had no other complaints. The excised appendices of these two patients appeared normal on gross examination.On light microscopy, both appendices showed a thick layer of spirochetes on the luminal side of the surface epithelium (Figure 1). They appeared as haematoxyphilic fibrillar material on H&E and were argyrophilic ...