Loss of expression of 5-hydroxymethylcytosine in CD30-positive cutaneous lymphoproliferative disorders.

BACKGROUND: The methylation of DNA at position 5 of cytosine, and the subsequent reduction in intracellular 5-hydroxymethylcytosine (5-hmC) levels, is a key epigenetic event in several cancers, including systemic lymphomas. However, no studies have analyzed this epigenetic marker in cutaneous lymphomas. Therefore, we aimed to analyze the expression of 5-hmC in cutaneous CD30-positive lymphoproliferative disorders and compare it with a control group composed of reactive infectious and inflammatory disorders with CD30-positive cells. METHODS: Retrospective case series study with immunohistochemical analysis using anti-CD30 and anti-5-hmC antibodies in control (n = 19), lymphomatoid papulosis (LyP) (n = 27) and primary cutaneous anaplastic large cell lymphoma (ALCL) (n = 14) specimens. RESULTS: Complete loss of 5-hmC nuclear staining by CD30+ cells was observed in 63% of LyP cases, 57% of ALCL cases and 0% of control cases. CONCLUSIONS: The presence of 5-hmC+ and CD30+ lymphocytes was highly suggestive of a benign process. In contrast, loss of 5-hmC nuclear staining was highly suggestive of a lymphoproliferative disorder (ALCL or LyP). Under these circumstances, the use of 5-hmC staining can be a useful adjunctive tool for discriminating between neoplastic CD30+ lymphoproliferations and inflammatory/infectious simulators harboring reactive CD30+ cells.

Immunohistochemical dual staining as an adjunct in assessment of mitotic activity in melanoma.

BACKGROUND: The mitotic rate was introduced as a major prognostic criterion for the staging of thin (≤1.0 mm) melanoma by the 2009 American Joint Committee on Cancer Staging and Classification (seventh edition). The detection of a single mitotic figure changes the tumor stage in thin melanoma. We sought to address the value of a dual staining to facilitate the determination of the mitotic rate and to assign the mitotic activity to melanocytes. METHODS: The mitotic rate of melanoma cells was determined by dual phosphohistone-H3 (PHH3)/Melan-A immunohistochemistry. Results were compared with PHH3 staining alone and conventional hematoxylin and eosin (H&E)-stained slides of 15 melanomas with a tumor thickness <1.0 mm. RESULTS: PHH3 staining clearly labeled cells in the mitotic cell cycle. The mitotic rate in the PHH3/Melan-A dual stain was equal to that derived by H&E staining. Time required for counting mitotic figures was significantly reduced. CONCLUSIONS: The evaluation of mitotic rate with an immunohistochemical dual stain is faster (mean 63.0%) and more reliable than evaluation by routine H&E staining alone. Dual staining immunohistochemistry may be a useful additional tool to standardize the determination of mitotic rate and may be helpful in evaluation of challenging cases.

Necrotizing infundibular crystalline folliculitis: a clinicopathological study.

BACKGROUND: Necrotizing infundibular crystalline folliculitis (NICF) is a folliculocentric disorder associated with filamentous crystalline deposits, enclosed by parakeratotic columns within the partly necrotic follicular ostium and infundibulum. There are only very few data published about this disorder of unknown origin. OBJECTIVE: We sought to determine the clinicopathological features and pathogenetic aspects of NICF. METHODS: Clinicopathological characterization of 9 patients with NICF and a second group of 7 patients with coincidental findings of NICF in the vicinity of epithelial skin neoplasms was conducted. RESULTS: Clinically, NICF is characterized by multiple waxy papules with predilection for the forehead (56%), neck, and back. Birefringent crystalline deposits were present in the follicular ostia and enclosed by parakeratotic columns in all cases. The necrosis of follicular epithelium was found in 89% and perifollicular neutrophilic infiltrate in 22% of the biopsy specimens. Both yeasts and gram-positive bacteria were identified within the affected follicles in 56% in the first group and 86% in the second group of coincidental NICF. LIMITATION: This was a single-center retrospective study. CONCLUSIONS: NICF is both a distinct entity and an epiphenomenon in the context of other disorders. In regard to the common association with yeasts and gram-positive bacteria in the affected follicles, we hypothesize that NICF is pathogenetically linked to these organisms, which is supported by resolution of the lesions after topical or systemic antimycotic treatment.

Merkel cell polyomavirus is present in common warts and carcinoma in situ of the skin.

Polyomaviruses have been linked to diseases of immunosuppressed patients. We sought to determine the prevalence of Merkel cell polyomavirus in benign epithelial skin neoplasms and nonmelanoma skin cancer of immunosuppressed renal transplant recipients and long-term dialysis patients. Merkel cell polyomavirus DNA was detected by polymerase chain reaction (PCR) in 2 (10%) of 20 patients, in carcinomas in situ (Bowen's disease). In one of our patients with Merkel cell polyomavirus-positive carcinoma in situ, 9 (39.1%) of 23 skin lesions at various anatomical locations tested positive for Merkel cell polyomavirus sequences by PCR, including all of his common warts (4/4), half of his carcinoma in situ lesions (3/6), and 2 of his 3 seborrheic keratoses. In a second cohort of immunosuppressed renal transplant recipients, Merkel cell polyomavirus DNA was found in 1 (6.3%) of 16 common warts and in 2 (9.5%) of 21 carcinomas in situ. In immunocompetent individuals, Merkel cell polyomavirus DNA was found in 2 (6.7%) of 30 common warts and in 2 (8.3%) of 24 carcinomas in situ. DNA of other human polyomaviruses was not detected in any of the investigated skin neoplasms. We conclude that common warts and carcinomas in situ can be positive for Merkel cell polyomavirus in immunosuppressed as well as immunocompetent individuals. Remarkably, some of the Merkel cell polyomavirus-positive common warts did not contain human papillomavirus. Furthermore, Merkel cell polyomavirus can be found in various skin neoplasms of the same individual.

Basal cell carcinoma in a series of renal transplant recipients: epidemiology and clinicopathologic features.

BACKGROUND: Basal cell carcinoma (BCC) is the most common malignancy among Caucasians worldwide. The risk of BCC is 10-16 times higher among immunosuppressed transplant recipients compared with the general population. OBJECTIVE: To analyze the incidence, clinical presentation, histologic features, treatment and recurrence rate of BCC in a cohort of 69 renal transplant recipients (RTRs; 53 male). METHODS: Retrospective population-based cohort study of immunosuppressed RTRs. RESULTS: Ten of 69 patients (14.5%, five male) developed a total of 17 BCCs, mostly on the head. Mean age at first diagnosis of BCC was 65.5 +/- 8.5 years, and latency between kidney transplantation and diagnosis of the first BCC was 11.1 +/- 6.3 years (mean +/- SD). The risk of female RTRs to develop BCCs appeared to be three times higher than the risk of male RTRs, and female RTRs developed BCCs earlier after transplantation. Nodular BCC was the most common histologic subtype. Most BCCs in these RTRs were treated by complete surgical excision. Recurrence after surgical excision was observed in one of the 10 patients (10%). CONCLUSION: Our results suggest female RTRs to be at higher risk to develop cutaneous BCCs than male RTRs. There are no differences in localization and clinicopathologic presentation of BCCs developing in RTRs compared with immunocompetent patients. Therefore, BCCs in RTRs do not require different treatment than in other patient groups. As patients tend to develop a second BCC, close follow-up is mandatory.

C3d immunohistochemistry on formalin-fixed tissue is a valuable tool in the diagnosis of bullous pemphigoid of the skin.

BACKGROUND: Direct immunofluorescence (DIF) testing is an important procedure in the diagnosis of autoimmune bullous dermatoses. We investigated the expression of C3d in formalin-fixed, paraffin-embedded tissue of autoimmune bullous dermatoses. METHODS: The immunohistochemical expression of C3d in bullous pemphigoid (BP) (n = 32), pemphigoid gestationis (PG) (n = 3), pemphigus (n = 14), dermatitis herpetiformis Duhring (DHD) (n = 10), linear immunoglobulin A (IgA) dermatosis (n = 4), mixed forms of BP and linear IgA dermatosis (n = 2), and 44 controls was analyzed on formalin-fixed tissue. RESULTS: Thirty-one of 32 cases (97%) of BP and 3 out of 3 cases (100%) of PG showed a linear positivity of C3d along the basement membrane. Only 3 out of 14 (21%) cases of pemphigus showed an intraepidermal intercellular expression of C3d. The two mixed forms of linear IgA dermatosis and BP showed a linear positivity of C3d along the basement membrane. All cases of DHD, linear IgA dermatosis and all of the controls were negative for C3d. CONCLUSIONS: C3d immunohistochemistry is a valuable tool in the diagnosis of BP and PG of the skin with a sensitivity of at least 97%. Mixed forms of linear IgA dermatosis, and BP, DHD and linear IgA dermatosis can only be identified by DIF. A positive result may prompt serologic confirmation of BP without further need for DIF.

Inflammatory monocytes are a reservoir for Merkel cell polyomavirus.

Merkel cell polyomavirus (MCPyV) is a recently discovered virus that is implicated in the oncogenesis of Merkel cell carcinoma (MCC). The route of dissemination and the reservoir(s) of MCPyV within the human body have not yet been identified. In this study we describe two patients with multiple MCPyV-positive inflammatory and neoplastic skin lesions at different anatomic sites. Patient 1 was suffering from psoriasis for many years and was diagnosed with MCC 7 years before this study. Patient 2 had developed numerous non-melanoma skin cancer lesions under post-transplant immunosuppression. In both patients, MCPyV DNA was detected in whole blood and in urine using PCR and direct sequencing of PCR products. When we analyzed different blood compartments, we found MCPyV exclusively in cell-free serum and in blood monocytes, but not in lymphocytes or granulocytes. Upon separate analysis of resident (CD14(lo)CD16(+)) and inflammatory (CD14(+)CD16(-)) monocytes, we detected MCPyV exclusively in inflammatory, but not in resident monocytes. Our findings raise the possibility that MCPyV persists in inflammatory monocytes and spreads along the migration routes of inflammatory monocytes. This points to intervention strategies to contain MCPyV. Moreover, blood or urine tests may serve as ancillary tests to confirm MCPyV infection in a clinical setting.

Borrelia in granuloma annulare, morphea and lichen sclerosus: a PCR-based study and review of the literature.

BACKGROUND: Morphea, granuloma annulare (GA) and lichen sclerosus et atrophicans (LSA) have also been suggested to be linked to Borrelia infection. Previous studies based on serologic data or detection of Borrelia by immunohistochemistry and polymerase chain reaction (PCR) reported contradictory results. Thus, we examined skin biopsies of morphea, GA and LSA by PCR to assess the prevalence of Borrelia DNA in an endemic area and to compare our results with data in the literature. METHODS: Amplification of DNA sequences of Borrelia burgdorferi sensu lato by nested PCR from formalin-fixed and paraffin-embedded skin biopsies of morphea, GA and LSA, followed by automated sequencing of amplification products. PCR-based studies on Borrelia species in these disorders published until July 2009 were retrieved by a literature search. RESULTS: Borrelia DNA was detected in 3 of 112 skin biopsies (2.7%) including one of 49 morphea biopsies (2.0%), one of 48 GA biopsies (2.1%) and one of 15 LSA biopsies (6.6%). Amplification products belonged to B. burgdorferi sensu stricto in two cases available for sequence analysis. CONCLUSIONS: The results of our and most of other PCR-based studies do not argue for a significant association of B. burgdorferi sensu lato with morphea, GA, LSA.

A rare case of atypical cellular neurothekeoma in a 68-year-old woman.

Cellular neurothekeoma is a benign dermal lesion of uncertain differentiation. The atypical variant of cellular neurothekeoma, characterized by features such as large size, deep penetration, diffusely infiltrative borders, vascular invasion, high mitotic rate and marked cytologic pleomorphism, has been very rarely reported in the literature. We present the clinical, histopathological and immunohistochemical profile of a new case of atypical cellular neurothekeoma in a 68-year-old female patient who was diagnosed with ductal breast carcinoma in situ before. An erythematous painless papule arose in her right breast, and tentative clinical diagnosis was orientated toward skin metastasis of breast cancer or fibroma. Upon histological examination, the lesion showed the histological and immunohistochemical features of atypical variant of cellular neurothekeoma with high mitotic rate, marked cellular pleomorphism and penetration into subcutaneous fat. A further unusual feature in our patient was her age, because she is the oldest patient reported in the literature with diagnosis of atypical cellular neurothekeoma so far. Prognosis remains uncertain because only few cases of atypical cellular neurothekeoma have been reported in the literature, with a very limited follow-up time. Our report contributes to a better characterization of the clinical and morphologic features of atypical cellular neurothekeoma.

The second international conference on sentinel node biopsy in mucosal head and neck cancer.

BACKGROUND: The Second International Conference on Sentinel Node Biopsy in Mucosal Head and Neck Cancer was hosted by the Department of Otorhinolaryngology, Head and Neck Surgery of the University Hospital in Zurich, Switzerland, from September 12 to 13, 2003. The aims of this conference were to present the results of validation studies and to achieve a consensus on methodological requirements. METHODS: More than 80 delegates from 20 countries attended the conference. The presented validation studies were summarized and compared with the literature. Consensus was achieved concerning requirements for lymphatic mapping and histopathologic work-up. RESULTS: Twenty centers presented results on 379 patients with cN0 disease. Sentinel nodes were identified in 366 (97%) of 379. Of these 366, 103 (29%) were positive for occult metastasis, and 263 (71%) were negative. Of those 263 patients, 11 patients (4%) showed nodal disease not revealed by the sentinel lymph node biopsy (SNB). The negative predictive value of a negative sentinel node for the remaining neck was 96%. The consensus conference resulted in the use of a radiotracer, lymphoscintigraphy, and a handheld gamma probe for lymphatic mapping as minimal requirements. The use of conventional hematoxylin and eosin staining and immunohistochemistry for cytokeratin is mandatory. Step-sectioning of the entire node at intervals of 150 mum is recommended. CONCLUSIONS: The conference attracted delegates from all over the world, thus underscoring the high interest in the topic. With regard to the presented data and the data from the literature, SNB for early oral and oropharyngeal cancer is sufficiently validated. The consensus conference resulted in the definition of minimal methodological requirements for accurate SNB.

Sarcomatoid salivary duct carcinoma.

The so-called sarcomatoid salivary duct carcinoma (SSDC) is one of the variants of salivary duct carcinoma (SDC). This neoplasm is characterized by the presence of both a carcinomatous and a sarcomatoid tumor component. The histology and nomenclature of such neoplasms has been a matter of debate for many years. The histologic, immunohistochemical, and electron microscopic findings including those of 4 previously described cases of SSDC are defined and the different attitudes concerning their etiology will be discussed. In addition, the fine-needle aspiration biopsy of such a case is presented for the first time. In analogy to typical SDC there seems to be a predilection for elderly men and a location in major salivary glands. The resected SSDC tumors measured between 1.5 and 3.5 cm. Histologically, each case was a composite of SDC and sarcomatoid carcinoma. Immunohistochemical positivity for epithelial membrane antigen (EMA) and cytokeratins (AE1/AE3, CAM 5.2) was shown in the sarcomatoid tumor component. The important cytomorphologic feature of SSDC is the presence of cohesive clusters and flat sheets of cells with a cribriform pattern, in combination with an atypical spindle cell component. The use of the term SSDC seems more appropriate than the term carcinosarcoma , as the immunohistochemical, electron microscopic, and recent molecular findings in this and other biphasic neoplasms imply a monoclonal origin.

Sentinel lymph node biopsy in thyroid tumors: a pilot study.

The purpose of this study was to assess the feasibility of sentinel lymph node (SLN) biopsy in thyroid neoplasms. Ten patients with uninodular thyroid disease and no evidence of lymph node metastases were examined. Lymph node mapping was performed by preoperative lymphoscintigraphy and intraoperative use of a hand-held gammaprobe. Following thyroidectomy, the SLN(s) were selectively excised and worked-up histologically for occult metastases. Overall detection of SLNs was possible in 50% of the cases with lymphoscintigraphy and in 100% with the gammaprobe. All SLNs in the lateral compartment and upper mediastinum were accurately detected with lymphoscintigraphy. One patient with a papillary carcinoma showed a metastasis in the SLN. One patient experienced temporary lesion of the recurrent laryngeal nerve. In conclusion, sentinel lymph node biopsy is technically feasible. The combination of lymphoscintigraphy and gammaprobe accurately reveals SLNs in the central and lateral compartment and in the mediastinum. Search for SLNs in the lower central compartment enhances the risk of injuring the recurrent laryngeal nerve. The clinical relevance of SLN biopsy in papillary thyroid cancer is unclear, and the subgroup of patients benefiting from it has still to be defined.

Expression of the extra domain B of fibronectin, a marker of angiogenesis, in head and neck tumors.

OBJECTIVES/HYPOTHESIS: The extra domain B (ED-B) of fibronectin, a naturally occurring marker of tissue remodeling and angiogenesis, is expressed in the majority of aggressive solid human tumors, whereas it is not detectable in normal vessels and tissues. STUDY DESIGN: In view of the diagnostic and therapeutic clinical applications of the L19 antibody, which is specific for the ED-B domain of fibronectin, a prospective immunohistochemical analysis of different head and neck tumors was performed. METHODS: In all, 82 head and neck tissue biopsy specimens were immunohistochemically analyzed using the L19 antibody. They consisted of 53 different malignant tumors, 8 benign tumors, 10 nontumoral lesions, and 11 normal control tissues. RESULTS: A strong positive staining with the L19 antibody could be observed in 87% of the investigated malignant tumors, in only 38% of the benign tumors, and in 20% of the nontumoral lesions (P <.0001). The extra domain B was completely absent in the normal control tissue samples. CONCLUSIONS: The results show that ED-B is abundantly expressed around the neovasculature and in the stroma of the majority of malignant tumors of the head and neck but is undetectable in normal tissues. The ED-B domain of fibronectin is a good-quality tumor-stroma-associated antigen that warrants clinical trials with antibody-based pharmaceuticals, including immunoscintigraphic investigations and radioimmunoguided surgery with the radiolabeled L19 antibody.

Tracheal lobular capillary hemangioma: a rare cause of recurrent hemoptysis.

Lobular capillary hemangioma (LCH) is a polypoid form of capillary hemangioma occurring on the skin and mucosal surfaces. While LCH of the oral and nasal cavity is a well-known entity, tracheal localization is extremely rare. We present the case of a 72-year-old woman with recurrent hemoptysis due to a small tumor of the proximal trachea. By endoscopic removal of the tumor by flexible bronchoscopy, the diagnosis of LCH was made, and during the following year there was no recurrent hemoptysis. To our knowledge, this is the first case of histologically proven LCH of the trachea.

Is there a role for positron emission tomography with 18F-fluorodeoxyglucose in the initial staging of nodal negative oral and oropharyngeal squamous cell carcinoma.

BACKGROUND: The aim of our study was to assess the value of positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) for the staging of clinically nodal negative necks in oral and oropharyngeal squamous cell carcinoma (SCC) using sentinel lymph node (SLN) biopsy and elective neck dissection (END) as "gold standard" for comparison. METHODS: Twelve patients (10 men, 2 women) with oral or oropharyngeal squamous cell carcinoma and no evidence of lymph node metastasis in the physical and radiologic examinations were eligible. At least 24 hours before surgery PET with FDG were performed. The SLN was localized by preoperative lymphoscintigraphy with 99m-Tc-Nanocoll and intraoperative use of a hand-held gamma-probe and selectively excised. All patients then underwent END. RESULTS: SLN and END revealed occult metastasis in 5 of 12 cases. SLN biopsy was accurately feasible in all 12 patients and diagnosed all 5 cases of occult metastasis (sensitivity and specificity of 100%). PET suggested two patients having occult metastasis, of which one turned out to be false positive (sensitivity 25%, specificity 88%). The mean size of the micrometastasis was 1.4 mm (range, 1.2-1.5 mm). CONCLUSIONS: PET with FDG turned out to have a poor sensitivity and specificity in revealing occult metastasis and has no role for the evaluation of otherwise clinically N0 necks. The failure to detect micrometastasis by PET is due to the technical limitations of resolution (4-5 mm). SLN biopsy, with END in cases of positive SLN, provides a highly accurate staging of N0 necks in oral and oropharyngeal carcinoma. Patients with negative SLN could be spared the risks and the morbidity of END.

Loss of heterozygosity at chromosome 6q23-25 correlates with clinical and histologic parameters in salivary gland adenoid cystic carcinoma.

The prognosis of salivary gland adenoid cystic carcinoma (ACC) depends on the clinical stage, the location of the primary tumor, and the histologic growth pattern. ACCs with a cribriform growth pattern have a better prognosis than those with a solid growth pattern; however, clear-cut grading criteria have not yet been established, and therefore prognostic indicators on a molecular level are of special interest. In order to analyze tumor tissue with different growth patterns, cribriform and solid tumor areas of 25 patients were microdissected and separately analyzed for loss of heterozygosity (LOH) at nine polymorphic microsatellite markers located between 6q14 and 6q27. LOH was detected in 19/25 (76%) patients and LOH rates were highest at markers D6S441, D6S310, D6S311 and UTRN, which are located at 6q23-25. Combined analysis of LOH at these four markers shows that in primary tumor subtype foci with cribriform growth pattern LOH is associated with high TNM stages (P<0.01), high T stages (P=0.01), positive lymph node status (P=0.03), an unfavorable disease course (P=0.02), and the presence of >10% solid growth pattern (P=0.05). In contrast, in primary tumor subtype foci with solid growth pattern, no significant differences in LOH rates were found in patients from prognostically and histologically favorable versus unfavorable patient groups. The frequent occurrence of LOH at 6q23-25 and the correlation of LOH rates with prognostic parameters indicate that a prognostically important tumor suppressor gene is located in this chromosomal area.

Combined comparative genomic hybridization and genomic microarray for detection of gene amplifications in pulmonary artery intimal sarcomas and adrenocortical tumors.

Identification of gene amplifications in human tumors is important for the understanding of tumorigenesis and may lead to discovery of diagnostic and prognostic markers. In this study, we used a microarray-based comparative genomic hybridization (CGH) technique, combined with conventional CGH, to identify gene amplifications in 43 tumors including eight pulmonary artery intimal sarcomas and 35 adrenocortical tumors. Conventional CGH revealed gains or amplifications of 12q13-q15 in six sarcomas and in two adrenocortical carcinomas. Using microarrays, we demonstrated that, among genes located on 12q13-q15, SAS/CDK4 were amplified in six sarcomas, and MDM2 and GLI in five and four sarcomas, respectively. The two adrenocortical tumors showed coamplifications of SAS/CDK4 and MDM2. Furthermore, PDGFRA (located on 4q12) amplification was identified in five sarcomas. Our data demonstrate: (1) amplifications of SAS/CDK4, MDM2, GLI, and PDGFRA are strongly associated with the tumorigenesis of pulmonary artery intimal sarcomas, whereas SAS/CDK4 and MDM2 coamplification may contribute to the progression of adrenocortical tumors; (2) microarray-based CGH is a useful tool for simultaneous detection of multiple gene amplifications, with a high sensitivity and resolution compared to that of conventional CGH.

Histopathological features of occult metastasis detected by sentinel lymph node biopsy in oral and oropharyngeal squamous cell carcinoma.

OBJECTIVES: Sentinel lymph node biopsy has been introduced for head and neck cancer with promising results. Research in breast cancer has revealed different histopathological features of occult lymph node metastasis with possibly different clinical and prognostic implications. The aim of the study was to evaluate the histopathological features of occult metastasis detected by sentinel lymph node in oral and oropharyngeal squamous cell carcinoma. STUDY DESIGN: Prospective. METHODS: According to Hermanek (5), occult metastasis was differentiated into isolated tumor cells and infiltration of lymph node parenchyma smaller than 2 mm in diameter (micrometastasis) and larger than 2 mm in diameter (metastasis). RESULTS: Occult metastases were found in 6 of 19 (32%) sentinel lymph nodes. Three patients showed micrometastasis with a mean size of 1.4 mm (range, 1.2-1.5 mm), the first with three separate micrometastases within the same sentinel lymph node, the second with an additional cluster of isolated tumor cells within the same sentinel lymph node, and the third with an additional micrometastasis in one lymph node of the elective neck dissection. Two patients had macrometastasis (3.4 and 8 mm), both with multiple metastases in the elective neck dissection. One patient had two clusters of isolated tumor cells in the sentinel lymph node and an additional cluster of isolated tumor cells in one lymph node of the elective neck dissection. CONCLUSIONS: Occult metastasis can be subdivided histopathologically in isolated tumor cells, micrometastasis, and macrometastasis. We present the first study describing a great variety of these subtypes in sentinel lymph nodes from head and neck squamous cell carcinoma. Because the independent prognostic factor and clinical relevance of these subtypes is still unclear, we emphasize the importance of reporting these findings uniformly and according to well-established criteria.