Simon Nayler

Follicular dendritic cell sarcoma

The goal of this study was to characterize the clinicopathologic features of follicular dendritic cell sarcoma, a very uncommon neoplasm.

Composite hemangioendothelioma: a complex, low-grade vascular lesion mimicking angiosarcoma.

Eight cases of a previously uncharacterized vascular neoplasm, showing varying combinations of benign, low-grade malignant, and malignant vascular components are described. Seven tumors occurred in the dermis and/or subcutis and one occurred in the oral submucosa. The patients were all adults with a median age of 39.5 years (range, 21-71 years). Five patients were men. The tumors arose predominantly in the hands and feet, and the lesions were usually of several years duration. The tumors were composed of a complex admixture of histologic components that varied from tumor to tumor, such that no two tumors looked precisely the same. This was due to variation in the proportions of each component as well as the manner in which each component was distributed throughout each lesion. The predominant histologic components were epithelioid hemangioendothelioma (HE) and retiform HE, which were each present in seven of the tumors. Areas of spindle cell HE were identified in four lesions. Angiosarcoma-like elements were identified in seven tumors. One of the tumors was associated with an arteriovenous malformation and one was associated with an area of lymphangioma circumscriptum. Of six cases with follow up (median duration, 6.5 years), three have recurred locally and, to date, only one has metastasized. We think composite HE is best regarded as a low-grade malignant vascular neoplasm, and the available data suggest that it behaves more favorably than conventional angiosarcoma. The existence of these composite lesions has led to careful reexamination of the concept of HE. The term HE, in that it is currently synonymous with a low-grade malignant vascular tumor, should be reserved for lesions that have true metastatic potential, albeit with low frequency.

Sialadenosis: A presenting sign in bulimia

Sialadenosis refers to noninflammatory, often recurrent, enlargement of the salivary glands, most frequently the parotids, which is almost always associated with an underlying systemic disorder. These include diabetes, alcoholism, malnutrition, anorexia nervosa, and bulimia. It is thought that the various causes of sialadenosis all result in a common pathogenetic effect in that they produce a peripheral autonomic neuropathy which is responsible for disordered metabolism and secretion, resulting in acinar enlargement.

Spindle epithelial tumour with thymus‐like element (SETTLE): the predominantly monophasic variant

To describe two cases of spindle epithelial tumour with thymus‐like element (SETTLE) which are composed predominantly of spindle cells. In addition, to highlight some unusual histological features in SETTLE and discuss its separation from histological mimics.

Malignant transformation in a schwannoma

The two most common benign neoplasms of peripheral nerve sheath are neurofibromas and schwannomas (neurilemmomas). Malignant change is well known to occur in neurofibromas, in the setting of type 1 neurofibromatosis. In this context, up to 5% of neurofibromas undergo malignant transformation, this being a complex multistep process involving the NF-1 gene, and the p53 gene. Malignant transformation of schwannomas, in contrast, is an exceedingly rare occurrence, with no hereditary predisposition. It has been stated that malignant change is so rare, that for practical purposes it may be disregarded. In a recent review of 32 previously reported cases, 25 were found to be unacceptable examples; hence there are, to our knowledge, only nine acceptable examples of malignant transformation in benign schwannomas. We present a case of sarcomatous change within a benign schwannoma probably representing the earliest example yet reported.

Cytopathology of follicular dendritic cell tumors

Follicular dendritic cell tumors are rarely described entities, arising from antigen‐presenting immune accessory cells, found within B‐lymphocyte follicles in nodal and extranodal sites. We report two cases, one associated with Castlemans disease, in whom fine‐needle aspiration biopsy was performed followed by surgical biopsy. The diagnosis was confirmed using immunoreactivity with CD21 and CD35 antibodies and by ultrastructural demonstration of interdigitating cell processes with desmosomes.

Proximal epithelioid sarcoma—a misnomer

vascular graft, tricuspid patch and dural substitute. It has been used in the past as a synthetic prosthesis for augmentation mammoplasty. Although polyvinyl breast implants were abandoned in the mid-1960s with the introduction of silicon gel breast prostheses, it is still possible that the surgeon may encounter a patient with these sponge implants in place. Currently, the main uses of Ivalon are for vascular embolization and rectopexy. It is pliable, easily handled when wet, has good tensile strength and is compressible. Unfortunately, Ivalon stiffens with time and has a strong tendency to induce mineral deposition on its surface or it may become friable and deteriorate. Morphological characterization of polyvinyl sponge breast prostheses and its complications are well described in the literature. Thompson et al. described intraperitoneal Ivalon mimicking peritoneal malignancy after plugged percutaneous liver biopsy in a 20-year-old woman. To our knowledge, this is the second case in the literature of Ivalon sponge presenting as an extrarectal mass. This case is unusual in that the clinical, radiological and frozen section diagnoses all suggested a bony neoplasm. It is important that clinicians and pathologists are aware of this pseudotumour which might cause diagnostic confusion with more serious bony lesions.

Biotin inclusions: a potential pitfall in immunohistochemistry

Sir : In the November 1997 issue of Histopathology, Bussolati et al. describe the restoration of endogenous biotin reactivity following antigen retrieval (using pressure cooking and to a lesser extent microwave retrieval). The authors suggest that blocking of endogenous biotin by sequential avidin–biotin treatment prevents the erroneous detection of biotin. Intra-nuclear biotin inclusions have been previously misinterpreted to be those of Herpes simplex virus (HSV), using the streptavidin–biotin complex (StrepABC). We have also described biotin intranuclear inclusions in gestational endometria closely resembling HSV inclusions. This error can be easily avoided by paying careful attention to the negative control. We have noted the negative control to be invariably positive, due to the presence of endogenous biotin, with the StrepABC immunodetection system. This false positive immunoreaction should be the clue to the alert pathologist that there is endogenous biotin reactivity. Despite attempts to block endogenous biotin with free avidin and biotin as recommended, we have demonstrated residual positivity in the negative control, using the StrepABC system. We have also compared the alkaline-phosphatase– anti-alkaline phosphatase (APAAP) and the peroxidase– anti-peroxidase (PAP) detection systems and found that whilst the negative control was negative with the former, there was aberrant immunoreactivity with the PAP system. Curiously this was eliminated with microwave pretreatment prior to immunohistochemistry. These curious results serve to underscore the complexities of antigen retrieval. We use retrieval methods such as pressure cooking, microwave technology and even ultrasound, barely understanding the mechanisms of antigen retrieval. It is inevitable that aberrant and puzzling results are obtained. It is imperative that diagnostic pathologists interpret immunohistochemical findings in the light of positive and negative controls, and also with full knowledge of the pitfalls and limitations of the varying detection systems used in their laboratories. We advocate that the optimal detection system for immunohistochemistry in the tissues containing endogenous biotin, as so comprehensively demonstrated by Bussolati et al. is either the APAAP or PAP immunodetection system (the latter with microwave pretreatment), rather than the StrepABC method. Embarrassing and potentially dangerous errors can thus be avoided. S J Nayler S Goetsch K Cooper

Large vessel adventitial vasculitis characterizes patients with critical lower limb ischemia with as compared to without human immunodeficiency virus infection.

Objectives Whether a human immunodeficiency virus (HIV)-associated vasculitis in-part accounts for occlusive large artery disease remains uncertain. We aimed to identify the histopathological features that characterize large vessel changes in HIV sero-positive as compared to sero-negative patients with critical lower limb ischemia (CLI). Materials and Methods Femoral arteries obtained from 10 HIV positive and 10 HIV negative black African male patients admitted to a single vascular unit with CLI requiring above knee amputation were subjected to histopathological assessment. None of the HIV positive patients were receiving antiretroviral therapy. Results As compared to HIV negative patients with CLI, HIV positive patients were younger (p<0.01) and had a lower prevalence of hypertension (10 vs 90%, p<0.005) and diabetes mellitus (0 vs 50%, p<0.05), but a similar proportion of patients previously or currently smoked (80 vs 60%). 90% of HIV positive patients, but no HIV negative patient had evidence of adventitial leukocytoclastic vasculitis of the vasa vasorum (p<0.0001). In addition, 70% of HIV positive, but no HIV negative patient had evidence of adventitial slit-like vessels. Whilst T-lymphocytes were noted in the adventitia in 80% of HIV positive patients, T-lymphocytes were noted only in the intima in HIV negative patients. The presence of femoral artery calcified multilayered fibro-atheroma was noted in 40% of HIV positive and 90% of HIV negative patients with CLI. Conclusions An adventitial vasculitis which characterizes large artery changes in CLI in HIV-infected as compared to non-infected patients, may contribute toward HIV-associated occlusive large artery disease.

Cryptogenic Cirrhosis and Hepatopulmonary Syndrome in a Boy with Hepatic Hemangioma in Botswana: A Case Report and Review of the Literature

Hepatic hemangiomas are considered to be the most common benign tumors of the liver. They are often found incidentally while investigating for other causes of liver disease. Hemangiomas that are less than 10 cm are not expected to cause any problems. Typically, they do not enlarge and, apart from regular follow-up, no definitive treatment is indicated. This is a posthumous case report of a male child with a medium-sized hemangioma from infancy, complicated by cryptogenic cirrhosis and hepatopulmonary syndrome. It demonstrates the challenges of managing a child with such complicated conditions in a resource-limited setting.