Primary intra-renal desmoplastic small round cell tumor: expanding the histologic spectrum, with special emphasis on the differential diagnostic considerations.

Intra-abdominal desmoplastic small round cell tumor (DSRCT) is a rare, aggressive tumor affecting adolescent and young males. DSRCT presenting as a primary renal mass in the absence of visceral or serosal involvement is extremely rare. Herein, we present the pathologic and molecular findings in the case of a young man who presented with a large renal mass without any visceral or serosal involvement. Noticeably, the tumor lacked prominent desmoplastic stroma and only focally expressed cytokeratin, both of which are considered characteristic histologic features for this tumor. Fluorescence in situ hybridization studies using an EWSR1 break-apart probe confirmed the presence of a rearrangement involving the EWSR1 locus and RT-PCR demonstrated the presence of an EWSR1-WT1 fusion transcript associated with the t(11;22) rearrangement, which supported a diagnosis of DSRCT. We also discuss the differential diagnostic considerations faced by the pathologist in the workup of small round cell neoplasms of the kidney.

Gastroduodenal Cryptococcus in an AIDS Patient Presenting With Melena.

Gastrointestinal cryptococcosis is extremely rare with only a few case reports found in the literature and involvement primarily identified post-mortem. This is a case of 54-year-old man with a 20-year history of poorly controlled human immunodeficiency virus presented with constitutional symptoms along with melena. Diagnostic work up with esophagogastroduodenoscopy showed 4 irregular ulcers in the stomach notable for red-pigmented lesions within the ulcers, erythematous mucosa in the antrum and patchy friable mucosa in the duodenum. H&E staining and Mucicarmine staining showed findings consistent with C. neoformans. Blood culture and cerebrospinal fluid studies also revealed C. neoformans. Cryptococcus neoformans is an AIDS defining illness that most commonly presents as meningoencephalitis and pneumonitis. Key management principles includes: induction of antifungal therapy followed by consolidation and maintenance; management of elevated intracranial pressure and immune reconstitution inflammatory syndrome. Although the organism can infect nearly all organs, gastrointestinal involvement is rarely described. Our case highlights the fact that gastrointestinal C. neoformans infection can be associated with upper gastrointestinal symptoms and may be the initial presentation of disseminated cryptococcosis.

Re-examination of features to distinguish polyarteritis nodosa from superficial thrombophlebitis.

The correct identification of vessel type is crucial in distinguishing cutaneous polyarteritis nodosa from superficial thrombophlebitis. As the treatment and prognosis of these conditions are very different, correct diagnosis is critical, but they have overlapping clinical and histopathologic features, which can sometimes make the distinction difficult. Features commonly used to distinguish an artery from vein include vessel shape and diameter, the presence or absence of an internal elastic lamina, smooth muscle pattern, and the presence or absence of valves. Recently, it has been proposed that the amount and distribution of elastic fibers in the medial muscular layer are the most reliable features to make this distinction. The first part of this study used prosector-identified vessels to determine which of these features is most sensitive and specific for identifying an artery and vein. A total of 19 arteries and 16 veins were dissected from autopsy and amputation specimens. For each specimen, the smooth muscle pattern, elastic fiber pattern, the presence of valves, and the presence or absence of an internal elastic membrane were determined. The quantity of elastic fibers in the muscular wall of each sample was also determined. Although the elastic fiber pattern was the most specific feature in identifying a vein, it suffered from low sensitivity (43.8%). The smooth muscle pattern had the highest combined sensitivity and specificity. In the second part of this study, the histologic features listed above were examined in previously diagnosed cases of superficial thrombophlebitis and arteritis. When inflammation is present within and around the wall of the vessel, all of the studied histologic features become less reliable, and the interobserver reliability of distinguishing arteritis from thrombophlebitis was low. Our findings suggest that no single histopathologic feature is completely reliable and combining the histopathologic features with clinicopathologic correlation is essential for correct vessel identification.

Smooth muscle pattern is more reliable than the presence or absence of an internal elastic lamina in distinguishing an artery from a vein.

BACKGROUND: Major pathology textbooks suggest that the shape of the vessel and the presence or absence of an internal elastic lamina are the best means to distinguish an artery from a vein. Because the shape of the vessel is highly dependent upon the plane of section, the internal elastic lamina is often cited as a more reliable criterion. After evaluating a patient with superficial thrombophlebitis, in whom these conventional criteria had led to a misdiagnosis of polyarteritis nodosa, we sought to determine whether the pattern of smooth muscle in the media is a more sensitive discriminator between an artery and a vein. METHODS: Anatomically identified arteries and veins were harvested from extremity amputation specimens and stored autopsy organ specimens and reviewed by two dermatopathologists who were blinded to the gross pathologist's impression. The biopsies were assessed for the smooth muscle pattern and the presence or absence of an internal elastic lamina. RESULTS: Forty-seven of the 50 cases (94%) were concordant with the pathologist's gross impression using only the smooth muscle pattern to differentiate an artery from a vein. On the basis of the presence or absence of an internal elastic lamina, 41 of 50 cases (82%) were concordant with the prosector's designation of the vessel. LIMITATIONS: Vessels were harvested from a variety of sites, with lower extremity vessels predominating. There may be some regional variability not addressed in this study. CONCLUSION: In this study, the pattern of muscle fibers within the vascular media discriminated between arteries and veins better than assessment of the presence or absence of an internal elastic lamina. Although no single criterion is 100% reliable, assessment of both these criteria may minimize the risk of misinterpreting vessels in the deep dermis and subcutis.

Safety of band ligator use in the small bowel and the colon.

BACKGROUND: Endoscopic band ligation for bleeding small-bowel vascular lesions has been reported as safe and efficacious based on small case series. There have been several other published case reports of band ligators used for bleeding lesions, usually Dieulafoy's lesions, in the stomach, the proximal small bowel, and the colon. In addition, this method has been used for postpolypectomy bleeding stalks. There has never been a critical look at the anatomic consequences of banding in the thinner sections of bowel. METHOD: The purpose of this study is to define the anatomic and histologic consequences of applying band ligator devices to the small and the large bowel. Fresh surgical specimens, both large and small bowel, that were excised because of neoplastic lesions were transported to our endoscopy unit where one end of the intact bowel was sutured shut. A standard upper endoscope was passed via the open end, and the bowel was closed tightly with rubber band ties. The bowel then was insufflated, and band ligators were applied to unaffected mucosa by using a standard technique. Photodocumentation from inside and outside the bowel was obtained. Some of the band polyps were cut above the band, and some were cut below the band in the fresh state. Some were fixed in formalin and examined microscopically. Histologic sectioning occurred at the level of the bands. RESULTS: The results were striking in that there were large holes (1 cm) in the fresh ileum specimen. There was gross serosal entrapment manifested by visible puckers on the outer surfaces of the specimens, especially in the small bowel and the right colon. The left colon, anatomically thicker, was less affected. The histologic evaluation revealed inclusion by the band ligator of the muscularis propria and serosa on the small bowel, the muscularis propria in the right colon, and the submucosa in the left colon. CONCLUSIONS: Based on these findings, we conclude that band ligator devices are not safe in the small bowel and the right colon but probably are safe in the thicker left colon.

The accuracy of the report of hepatic steatosis on ultrasonography in patients infected with hepatitis C in a clinical setting: a retrospective observational study.

BACKGROUND: Steatosis is occasionally reported during screening ultrasonography in patients with hepatitis C virus (HCV). We conducted a retrospective observational study to assess the factors associated with steatosis on ultrasonography and the relationship between steatosis on ultrasound versus biopsy in patients infected with HCV in a clinical setting. Our hypothesis was ultrasonography would perform poorly for the detection of steatosis outside of the context of a controlled study, primarily due to false-positive results caused by hepatic fibrosis and inflammation. METHODS: A retrospective review of ultrasound reports was conducted on patients infected with HCV in a tertiary care gastroenterology clinic. Reports were reviewed for the specific documentation of the presence of steatosis. Baseline clinical and histologic parameters were recorded, and compared for patients with vs. without steatosis. Multiple logistic regression analysis was performed on these baseline variables. Liver biopsies were reviewed by two pathologists, and graded for steatosis. Steatosis on biopsy was compared to steatosis on ultrasound report, and the performance characteristics of ultrasonography were calculated, using biopsy as the gold standard. RESULTS: Ultrasound reports were available on 164 patients. Patients with steatosis on ultrasound had a higher incidence of the following parameters compared to patients without steatosis: diabetes (12/49 [24%] vs. 7/115 [6%], p < 0.001), fibrosis stage > 2 (15/48 [31%] vs. 16/110 [15%], p = 0.02), histologic grade > 2 (19/48 [40%] vs. 17/103 [17%], p = 0.002), and ALT (129.5 +/- 89.0 IU/L vs. 94.3 +/- 87.0 IU/L, p = 0.01). Histologic grade was the only factor independently associated with steatosis with multivariate analysis. When compared to the histologic diagnosis of steatosis (n = 122), ultrasonography had a substantial number of false-positive and false-negative results. In patients with a normal ultrasound, 8/82 (10%) had > 30% steatosis on biopsy. Among patients with steatosis reported on ultrasound, only 12/40 (30%) had > 30% steatosis on biopsy review. CONCLUSION: Steatosis on ultrasound is associated with markers of inflammation and fibrosis in HCV-infected patients, but does not consistently correlate with steatosis on biopsy outside of the context of a controlled study. Clinicians should be skeptical of the definitive diagnosis of steatosis on hepatic ultrasonography.

Atypical junctional melanocytic proliferations in benign lichenoid keratosis.

Melanocytic lesions with lichenoid regression may mimic a benign lichenoid keratosis (BLK) histologically. A total of 336 BLKs were reviewed and deeper sections obtained to determine the frequency of this phenomenon. Two cases (0.6%) showed at least 1 melanocytic nest or junctional multinucleated melanocyte (starburst melanocyte) on deeper sections confirmed by MART-1 immunostaining. Both of these cases demonstrated solar elastosis, and 1 case had an effaced rete ridge pattern. Not included in the histological study are 5 additional cases in which the initial slide showed only lichenoid dermatitis, but deeper sections obtained before to the initial sign-out revealed a melanocytic proliferation. These 5 cases would have been signed out as "consistent with BLK" if deeper sections had not been obtained. Fluorescent in situ hybridization (FISH) was performed on 3 cases; in each case, the melanocytes demonstrated a loss of chromosome 9p21 DNA copy number. The finding of nests of genetically altered melanocytes on severely sun-damaged skin strongly suggests that these cases represent lichenoid regression of melanoma in situ. Pathologists should approach a diagnosis of BLK cautiously in the setting of severely sun-damaged skin.