Philip E. LeBoit

Scleromyxoedema-like cutaneous diseases in renal-dialysis patients

15 renal dialysis patients have been identified with a skin condition characterised by thickening and hardening of the skin of the extremities and an increase in dermal fibroblast-like cells associated with collagen remodelling and mucin deposition. The disease closely resembles scleromyxoedema, yet has significant enough clinical and histopathological differences to warrant its designation as a new clinicopathological entity.

Nephrogenic fibrosing dermopathy.

This report details the histopathologic findings in a unique fibrosing disorder that recently emerged among patients with renal disease. The affected patients were initially identified among recipients of renal transplants at a single institution, but later cases at other centers were identified, and included patients receiving renal dialysis for a variety of different kidney diseases. The cutaneous changes consisted largely of indurated plaques and papules on the extremities and trunk. Systemic findings seen in scleromyxedema, which the condition resembles in some respects, were absent. By routine microscopy, the findings range from a very subtle proliferation of dermal fibroblasts in early lesions, to a florid proliferation of fibroblasts and dendritic cells in fully developed cases. Thick collagen bundles with surrounding clefts are a prominent finding, and a variable increase in dermal mucin and elastic fibers was usually evident with special stains. CD-34 positive dermal dendrocytes were floridly abundant, with dendritic processes aligned with elastic fibers and around collagen bundles in a dense network. Factor XIIIa and CD-68 positive mono-and multinucleated cells are also present in increased numbers. Electron microscopy highlighted increased elastic fibers closely apposed to dendritic cell processes. The entire dermis was commonly involved, with increased spindle cells, collagen, mucin, and elastic fibers extending through the subcutis along the septa of fatty lobules. In some instances, the process resembled a sarcoma on histopathologic examination. The recent emergence of this condition and the apparent clustering of cases in specific dialysis centers initially suggested a possible infectious and/or toxic agent. To date, however, no such agent has been identified. We propose the term “nephrogenic fibrosing dermopathy (NFD)” until a specific cause can be identified.

Ultraviolet and ionizing radiation enhance the growth of BCCs and trichoblastomas in patched heterozygous knockout mice

Basal cell carcinomas, the commonest human skin cancers, consistently have abnormalities of the hedgehog signaling pathway and often have PTCH gene mutations. We report here that Ptch+/– mice develop primordial follicular neoplasms resembling human trichoblastomas, and that exposure to ultraviolet radiation or ionizing radiation results in an increase in the number and size of these tumors and a shift in their histologic features so that they more closely resemble human basal cell carcinoma. The mouse basal cell carcinomas and trichoblastoma-like tumors resemble human basal cell carcinomas in their loss of normal hemidesmosomal components, presence of p53 mutations, frequent loss of the normal remaining Ptch allele, and activation of hedgehog target gene transcription. The Ptch mutant mice provide the first mouse model, to our knowledge, of ultraviolet and ionizing radiation-induced basal cell carcinoma-like tumors, and also demonstrate that Ptch inactivation and hedgehog target gene activation are essential for basal cell carcinoma tumorigenesis.

Classifying Melanocytic Tumors Based on DNA Copy Number Changes

Melanoma and benign melanocytic nevi can overlap significantly in their histopathological presentation and misdiagnoses are common. To determine whether genetic criteria can be of diagnostic help we determined DNA copy number changes in 186 melanocytic tumors (132 melanomas and 54 benign nevi) using comparative genomic hybridization. We found highly significant differences between melanomas and nevi. Whereas 127 (96.2%) of the melanomas had some form of chromosomal aberration, only 7 (13.0%) of the benign nevi cases had aberrations. All seven cases with aberrations were Spitz nevi, in six of which the aberration was an isolated gain involving the entire short arm of chromosome 11. This aberration was not observed in any of the 132 melanomas. We also analyzed the 132 melanomas for genetic differences depending on anatomical site, Clarks histogenetic type, and sun-exposure pattern. We show that melanomas on acral sites have significantly more aberrations involving chromosomes 5p, 11q, 12q, and 15, as well as focused gene amplifications. Melanomas classified as lentigo maligna melanomas or as occurring on severely sun-damaged skin showed markedly more frequent losses of chromosomes 17p and 13q. This study shows a pattern of chromosomal aberration in melanoma that is distinct from melanocytic nevi and should be further evaluated as a diagnostic test for melanocytic lesions that are now ambiguous. In addition, we show marked differences in the genetic make-up of melanomas that depend on anatomical location and sun-exposure pattern indicating that potential therapeutic targets might vary among melanoma types.

Mutations and Copy Number Increase of HRAS in Spitz Nevi with Distinctive Histopathological Features

Spitz nevus is a benign melanocytic neoplasm that can be difficult or impossible to histologically distinguish from melanoma. We have recently described copy number increases of chromosome 11p in a subset of Spitz nevi. To study the molecular and histological features of this group, we studied 102 Spitz nevi for 11p copy number increases using fluorescence in situ hybridization (FISH) on tissue arrays. Copy number increases of at least threefold were found in 12 cases (11.8%) and involved the HRAS gene on chromosome 11p. Sequence analysis of HRAS showed frequent oncogenic mutations in cases with copy number increase (8/12 or 67%), contrasting with rare HRAS mutations in cases with normal HRAS copy numbers (1/21 or 5%, P: < 0.0001). Tumors with 11p copy number increases were larger, predominantly intradermal, had marked desmoplasia, characteristic cytological features, and had an infiltrating growth pattern. Proliferation rates in the majority of these cases were low to absent. HRAS activation by either mutation or copy number increase alone could explain several of the histological features that overlap with those of melanoma. We speculate that HRAS activation in the absence of co-operating additional genetic alterations drives the partially transformed melanocytes of these Spitz nevi into senescence or a stable growth arrest. Although there is no data suggesting that Spitz nevi with HRAS activation are at risk for progression to melanoma, future studies are warranted to assess their biological behavior more accurately.

Fluorescence In Situ Hybridization (FISH) as an Ancillary Diagnostic Tool in the Diagnosis of Melanoma

Although the clinical and pathologic diagnosis of some melanomas is clear-cut, there are many histopathologic simulators of melanoma that pose problems. Over-diagnosis of melanoma can lead to inappropriate therapy and psychologic burdens, whereas under-diagnosis can lead to inadequate treatment of a deadly cancer. We used existing data on DNA copy number alterations in melanoma to assemble panels of fluorescence in situ hybridization (FISH) probes suitable for the analysis of paraffin-embedded tissue. Using FISH data from a training set of 301 tumors, we established a discriminatory algorithm and validated it on an independent set of 169 unequivocal nevi and melanomas as well as 27 cases with ambiguous pathology, for which we had long-term follow-up data. An algorithm-using signal counts from a combination of 4 probes targeting chromosome 6p25, 6 centromere, 6q23, and 11q13 provided the highest diagnostic discrimination. This algorithm correctly classified melanoma with 86.7% sensitivity and 95.4% specificity in the validation cohort. The test also correctly identified as melanoma all 6 of 6 cases with ambiguous pathology that later metastasized. There was a significant difference in the metastasis free survival between test-positive and negative cases with ambiguous pathology (P=0.003). Sufficient chromosomal alterations are present in melanoma that a limited panel of FISH probes can distinguish most melanomas from most nevi, providing useful diagnostic information in cases that cannot be classified reliably by current methods. As a diagnostic aid to traditional histologic evaluation, this assay can have significant clinical impact and improve classification of melanocytic neoplasms with conflicting morphologic criteria.

Molecular Epidemiology of Bartonella Infections in Patients with Bacillary Angiomatosis–Peliosis

BACKGROUND Bacillary angiomatosis and bacillary peliosis are vascular proliferative manifestations of infection with species of the genus bartonella that occur predominantly in patients infected with the human immunodeficiency virus. Two species, B. henselae and B. quintana, have been associated with bacillary angiomatosis, but culture and speciation are difficult, and there has been little systematic evaluation of the species-specific disease characteristics. We studied 49 patients seen over eight years who were infected with bartonella species identified by molecular techniques and who had clinical lesions consistent with bacillary angiomatosis-peliosis. METHODS In this case-control study, a standardized questionnaire about exposures was administered to patients with bacillary angiomatosis-peliosis and to 96 matched controls. The infecting bartonella species were determined by molecular techniques. RESULTS Of the 49 patients with bacillary angiomatosis-peliosis, 26 (53 percent) were infected with B. henselae and 23 (47 percent) with B. quintana. Subcutaneous and lytic bone lesions were strongly associated with B. quintana, whereas peliosis hepatis was associated exclusively with B. henselae. Patients with B. henselae infection were identified throughout the study period and were epidemiologically linked to cat and flea exposure (P< or =0.004), whereas those with B. quintana were clustered and were characterized by low income (P=0.003), homelessness (P = 0.004), and exposure to lice (P= 0.03). Prior treatment with macrolide antibiotics appeared to be protective against infection with either species. CONCLUSIONS B. henselae and B. quintana, the organisms that cause bacillary angiomatosis-peliosis, are associated with different epidemiologic risk factors and with predilections for involvement of different organs.

Loss-of-function mutations in Notch receptors in cutaneous and lung squamous cell carcinoma

Squamous cell carcinomas (SCCs) are one of the most frequent forms of human malignancy, but, other than TP53 mutations, few causative somatic aberrations have been identified. We identified NOTCH1 or NOTCH2 mutations in ∼75% of cutaneous SCCs and in a lesser fraction of lung SCCs, defining a spectrum for the most prevalent tumor suppressor specific to these epithelial malignancies. Notch receptors normally transduce signals in response to ligands on neighboring cells, regulating metazoan lineage selection and developmental patterning. Our findings therefore illustrate a central role for disruption of microenvironmental communication in cancer progression. NOTCH aberrations include frameshift and nonsense mutations leading to receptor truncations as well as point substitutions in key functional domains that abrogate signaling in cell-based assays. Oncogenic gain-of-function mutations in NOTCH1 commonly occur in human T-cell lymphoblastic leukemia/lymphoma and B-cell chronic lymphocytic leukemia. The bifunctional role of Notch in human cancer thus emphasizes the context dependency of signaling outcomes and suggests that targeted inhibition of the Notch pathway may induce squamous epithelial malignancies.

Bacillary angiomatosis: the histopathology and differential diagnosis of a pseudoneoplastic infection in patients with human immunodeficiency virus disease

Cutaneous vascular proliferations that clinically or pathologically resemble Kaposis sarcoma, pyogenic granuloma, or histiocytoid (epithelioid) hemangioma may occur in patients with human immunodeficiency virus infection. These lesions, which respond well to antibiotic therapy, harbor bacilli similar to the agent of cat scratch disease. We evaluated 21 biopsy specimens from 13 patients with this condition, which we have called “bacillary angiomatosis.” The architecture resembled that of lobular capillary hemangioma (pyogenic granuloma), but the endothelial cells were often larger, polygonal, and sometimes markedly atypical. The presence of neutrophils, leukocytoclastic debris, and granular material (bacteria), and the absence of either spindled cells, bizarrely shaped vascular channels, or hyaline globules help to distinguish bacillary angiomatosis from Kaposis sarcoma. By electron microscopy, the protuberant endothelial cells were different from those of histiocytoid hemangiomas in that aggregates of intermediate filaments were absent, while numerous Weibel-Palade bodies were present. The immuno phenotype of the endothelial cells was distinct from that of Kaposis sarcoma; almost all cells showed both Factor VIII RAg and Ulex europaeus lectin positivity. Enzyme histochemistry also showed a pattern distinct from Kaposis sarcoma. Bacillary angiomatosis presents a unique constellation of clinical and microscopic findings. It is important to be aware of these characteristics, because these lesions are easily treatable with antibiotic therapy.

Genetic Changes in Neoplasms Arising in Congenital Melanocytic Nevi : Differences Between Nodular Proliferations and Melanomas

Large congenital melanocytic nevi (CMN) are at an increased risk of developing melanoma. Several forms of secondary proliferations can arise in congenital nevi on rare occasions. Although some of these closely resemble melanoma both clinically and histologically, metastasis is rare. We used comparative genomic hybridization to analyze chromosomal aberrations in different types of proliferations arising in CMN and compared them to typical congenital nevi, clear-cut melanomas arising in congenital nevi, as well as primary cutaneous melanomas that were not associated with a CMN. Cases of CMN and CMN with secondary proliferations were assigned to six groups according to the predominant histological pattern: group I, bland congenital nevi (n = 6); group II, congenital nevi with foci of increased cellularity (n = 4); group III, CMN with a proliferation simulating superficial spreading melanoma in situ (n = 3); group IV, CMN with a proliferation simulating nodular melanoma (n = 9); group V, proliferating neurocristic hamartoma (n = 1); and group VI, melanoma arising in congenital nevus (n = 6). No aberrations were found in groups I to III, whereas seven of nine cases of group IV, and one of one case of group V, showed aberrations. In group IV six of seven cases with aberrations (86%) showed numerical aberrations of whole chromosomes exclusively. This pattern differed significantly from the findings in melanoma that arose within CMN (n = 6), group VI, or independent of CMN (n = 122) in which only 5% showed numerical changes only. The single case in group V showed aberrations similar to melanoma. The finding of frequent numerical chromosomal aberrations in atypical nodular proliferations arising in CMN identifies these as clonal neoplasms with a genomic instability consistent with a mitotic spindle checkpoint defect. This difference compared to the aberration pattern found in melanoma might explain their more benign clinical behavior and may be of diagnostic value in ambiguous cases.