Quantitative analysis of eosinophils in acute graft-versus-host disease compared with drug hypersensitivity reactions

The role of eosinophils in the differential diagnosis of inflammatory skin diseases

Eosinophils are known to be present in inflammatory skin diseases, but their diagnostic utility is not well established. Upon review of the published status of lesional eosinophils, several categories were identified. 1) Lesional eosinophils highly characteristic such that, in their absence, the pathologist may question the diagnosis. These include arthropod bite reactions and scabies, urticarial dermatitis, and other eosinophilic dermatoses. 2) Lesional eosinophils rare or absent, such that, in their presence, the pathologist may question the diagnosis. These include pityriasis lichenoides, graft versus host disease, and connective tissue disorders. 3) Lesional eosinophils variable and, while in some cases expected, are not required for diagnosis. These include drug reactions, atopic dermatitis and allergic contact dermatitis. 4) Lesional eosinophils variable and not expected but may be seen to a limited extent. These include lichen planus and psoriasis.

The Mixed Spongiotic and Interface Reaction Pattern: A Study of Clinical and Histopathologic Findings

BACKGROUND

Categorization of biopsy specimens into inflammatory reaction patterns is central to dermatopathologic assessment. Mixed inflammatory patterns are poorly characterized and may represent clinicopathologic challenges. The purpose of this study was to identify clinical and histopathologic findings associated with the mixed spongiotic-interface dermatitis (SID) histopathologic pattern.

METHODS

Fifty-one institutional biopsy specimens of SID were identified over a 2-year period by retrospective natural language search. Histopathologic and clinical features were identified.

RESULTS

The most common histopathologic features associated with SID were mild spongiosis (51%), focal vacuolar interface change (72%), lymphocytic exocytosis (92%), and superficial-dermal lymphocytic infiltrate (94%) with variable eosinophils (61%). Clinically, 80% of subjects presented with a symmetric morbilliform eruption. Polypharmacy (94%), immunosuppression (47%), and history of malignancy (47%) were common. The most common diagnoses were drug reaction (37%), possible drug reaction (12%), and viral exanthem (12%). Drug reaction with eosinophilia and systemic symptoms represented 25% of all confirmed cutaneous adverse drug reactions (CADR). Average time from drug initiation to symptom initiation was 20 days (SD: 22.3, range: 0-90); median disease duration was 25.5 days. Spongiotic vesicles and Langerhans cells were less common in patients with a strong clinicopathologic diagnosis of drug reaction compared to non-drug eruptions (p = 0.04).

CONCLUSIONS

The mixed SID pattern is commonly encountered in CADR but may represent a more subacute course, implying consideration for inciting medication(s) started before the typical 7- to 14-day window.

Histopathologic Features of Maculopapular Drug Eruption

Background: Cutaneous adverse drug reaction (CADR) is common in both inpatient and outpatient clinical settings and has been associated with a large variety of medications. Drug reactions represent a significant burden to the healthcare system due to increased hospital stay durations and associated costs. Moreover, some of these reactions may be life-threatening. The most common clinical manifestation of a CADR is a maculopapular drug eruption (MDE). Due to its many clinical mimics and associations with a variety of histopathologic patterns, maculopapular drug eruption is difficult to definitively diagnose from both a clinical and histopathological perspective. Summary: We reviewed the clinical and histopathologic features of 327 cases of MDE from several studies in the literature and summarized characteristic histopathologic findings and their frequencies of occurrence. We found that the most common and suggestive histopathologic features of MDE were epidermal spongiosis, lymphocytic infiltrate, and occasional necrotic keratinocytes; interface change at the DEJ; superficial perivascular and interstitial lymphocytic infiltrate with or without eosinophils and neutrophils in the mid-to-deep dermis and mild papillary dermal edema; and dilation of superficial vessels. The presence of multiple histopathologic patterns within the same tissue specimen is also suggestive of MDE. This review and analysis suggest that a biopsy may improve the diagnostic accuracy by both establishing common and uncommon features associated with MDE and reviewing features that help to exclude other causes of maculopapular eruption. Key Message: Histopathologic criteria for the diagnosis of MDE, while not entirely specific, may aid in establishing a differential that includes a drug eruption. Thus, a biopsy can be a helpful diagnostic tool when MDE is suspected by demonstrating findings suggestive of MDE or by ruling out clinical mimics. However, biopsy results cannot be used in isolation as clinical-pathologic correlation is paramount in MDE.

Real-Time Reflectance Confocal Microscopy of Cutaneous Graft-versus-Host Disease Correlates with Histopathology

Reflectance confocal microscopy (RCM) allows noninvasive, real-time evaluation of the skin at a resolution akin to histopathology (HP), but its application in cutaneous graft-versus-host disease (GVHD) has not been extensively assessed. We describe RCM features of cutaneous GVHD including acute (aGVHD), late acute, chronic (cGVHD; sclerotic and nonsclerotic subtypes), and inactive GVHD and correlate RCM with same-site HP for a subset of patients. Thirty-two adult and pediatric allogeneic hematopoietic cell transplantation (allo-HCT) recipients with cutaneous GVHD received RCM imaging of ≥1 lesions (n = 44), 13 of which necessitated skin biopsy. RCM images were deidentified and assessed by 2 RCM experts blinded to clinical and HP findings to reach a consensus on the features and patterns of the inflammatory dermatoses. Major RCM features (present in ≥65% of lesional sites) and patterns were reported. To determine the correlation between RCM and HP, detection of cellular features and patterns of inflammatory dermatoses were compared using percent agreement and prevalence-adjusted, bias-adjusted kappa estimates. Seven patients with early or late aGVHD (7 lesions) had irregular honeycombing, spongiosis, dermoepidermal junction (DEJ) and dermal inflammation, and melanophages; those with early aGVHD also had hyperkeratosis, dilated vessels, and coarse connective tissue. Both groups had an interface dermatitis pattern. Eighteen patients with nonsclerotic cGVHD (24 lesions) had irregular honeycombing, spongiosis, DEJ and dermal inflammation, dilated vessels, coarse connective tissue, and interface and spongiotic dermatitis patterns. Three sclerotic patients with cGVHD (7 lesions) had irregular honeycombing, DEJ and dermal inflammation with an interface dermatitis pattern. Four patients with inactive GVHD (6 lesions) showed minimal inflammation. RCM and HP had similar detection rates for 6 of 13 features and overall patterns important for diagnosis in 2 patients with late aGVHD (2 lesions; 15%) and 10 with nonsclerotic cGVHD (11 lesions; 85%) necessitating skin biopsy. RCM can detect features commonly reported in cutaneous GVHD and is comparable to HP. Additional characterization of cutaneous GVHD by RCM may enable future use in diagnosing, monitoring, or predicting disease in real time.

Immunohistochemical markers for histopathological diagnosis and differentiation of acute cutaneous graft-versus-host disease

Graft-versus-host disease (GvHD) is a major complication following stem-cell or solid-organ transplantation. Accurate diagnosis of cutaneous GvHD is challenging, given that drug eruptions and viral rashes may present with similar clinical/histological manifestations. Specific markers are not available. We performed the histological examination of biopsy samples from acute GvHD (aGvHD; n = 54), Stevens-Johnson syndrome/toxic epidermal necrolysis (SJS/TEN; n = 27), maculopapular drug eruption (MDE; n = 26) and healthy controls (n = 26). Samples of aGvHD showed a decrease in Langerhans cells (LC, p = 0.0001) and an increase in macrophages (MΦ, p = 0.0001) compared to healthy skin. Compared to SJS/TEN, MDE and healthy skin, aGvHD biopsies contained greater numbers of CD4⁺ and CD8⁺ T cells. The majority of CD4⁺ T-helper cells were localized in the upper dermis, whereas cytotoxic CD8⁺ T cells were found in the epidermis. Increased numbers of CD56⁺ natural killer (NK) cells in the upper dermis of aGvHD skin (p = 0.007) were not observed in controls or SJS/TEN and MDE. There were no differences in elafin staining between aGvHD and the latter two conditions. Acute GvHD appears to have a distinct inflammatory cell profile (T cells/NK cells) that may aid establishing in a more accurate diagnosis, especially when used to rule out differential diagnoses such as SJS/TEN or MDE.

Histopathologic and immunophenotypic features of cutaneous solid organ transplant-associated graft-vs-host disease: Comparison with acute hematopoietic cell transplant-associated graft-vs-host disease and cutaneous drug eruption

BACKGROUND

Although it is relatively common after hematopoietic cell transplant (HCT), graft-vs-host disease (GVHD) is a rare complication following solid organ transplantation (SOT).

METHODS

This study evaluated skin biopsy specimens from five cases of SOT GVHD, 15 cases of HCT GVHD, and 15 cases of cutaneous drug eruption. Immunohistochemical staining for CD3, CD4, CD8, T-bet, and GATA-3 was performed to examine the density and immune phenotype of skin-infiltrating lymphocytes.

RESULTS

Similar to HCT GVHD, the predominant histopathologic findings in skin biopsy specimens of SOT GVHD were widespread vacuolar interface dermatitis with scattered necrotic keratinocytes. However, the density of dermal inflammation was considerably higher in SOT GVHD. Features that were more predictive of a cutaneous drug eruption over GVHD included spongiosis, confluent parakeratosis, and many eosinophils. Involvement of the hair follicle epithelium was seen in all three disorders. Both forms of cutaneous GVHD showed a predominance of Th1 (CD3+/T-bet+) lymphocytes within the inflammatory infiltrates. This shift was more pronounced in SOT GVHD, particularly among intraepidermal T-cells.

CONCLUSIONS

SOT GVHD shares many histopathologic features with HCT GVHD. However, SOT GVHD has a greater tendency to develop brisk lichenoid inflammation.

Are apoptosis-determining techniques useful to establish an early diagnosis of acute graft-vs-host disease in pediatric patients under treatment with multiple drugs?

BACKGROUND

There are no pathognomonic histopathological features to distinguish acute graft-vs-host disease (aGVHD) from skin drug reactions (SDRs) in pediatric patients with multiple drug regimens that have received blood transfusions and/or transplants. We aimed to determine if the addition of apoptosis markers is helpful to distinguish aGVHD from SDRs in these patients.

METHODS

Skin biopsy specimens from patients with a clinical diagnosis of aGVHD or SDRs were evaluated for the presence of apoptotic bodies, satellitosis, interface damage, vasculitis, and inflammatory infiltrate on H&E stain. Information was completed with apoptotic markers (transferase-mediated dUTP nick end-labeling [TUNEL], bcl-2, and caspase-3).

RESULTS

The skin biopsy specimens of 32 patients with aGVHD and 11 with SDRs were included for study. Only the number of apoptotic keratinocytes per 10 high-power fields (hpf) showed a significant difference between both groups (P = 0.02); the presence of ≥4 apoptotic keratinocytes per 10 hpf was identified as the optimal cut-off point to discriminate aGVHD from SDRs. No SDRs cases had follicular apoptotic cells. TUNEL, bcl-2, and caspase-3 determination showed no difference between both groups.

CONCLUSIONS

The presence of ≥4 apoptotic keratinocytes per 10 hpf (in aGVHD) and the absence of follicular apoptotic cells (in SDRs) might be a useful marker to distinguish between them.

Common and critical inflammatory dermatoses every pathologist should know

Inflammatory dermatopathology remains a challenging area for surgical pathologists. Yet every surgical pathologist encounters inflammatory dermatoses as part of routine practice. This review will focus on selected diagnoses that are either commonly encountered in the routine practice of surgical pathology or are critically important. The following entities will be covered: spongiotic dermatoses, lichen simplex chronicus, and early lichen sclerosus in the setting of vulvar biopsies, as well as graft versus host disease, Stevens-Johnson syndrome/toxic epidermal necrolysis, granuloma anulare, pyoderma gangrenosum, and calciphylaxis. Practical points and key histologic features will be emphasized.

Drugs as a Frequent Cause of Acute Rash in Patients after CD34+-Selected Peripheral Blood Stem Cell Transplantation

Although histopathological differences have been reported between acute graft-versus-host disease (aGVHD) rash and non-aGVHD rash in CD34+-selected peripheral blood stem cell transplantation (PBSCT) recipients, skin biopsy alone is usually insufficient to determine rash etiology. As such, distinguishing inflammatory non-aGVHD rashes, such as drug eruptions, from cutaneous aGVHD after CD34+-selected PBSCT remains challenging and relies on clinical presentation. This study aimed to identify etiologies of skin rash in the first year after CD34+-selected PBSCT and to assess whether laboratory serologic markers, transplant characteristics, and rash morphology and symptomatology aid in differentiation of cutaneous aGVHD rash versus non-aGVHD rash. We conducted a retrospective study of 243 adult patients who underwent CD34+-selected PBSCT at Memorial Sloan Kettering Cancer Center between 2008 and 2011. Among this cohort of transplant recipients, only 43 patients (17.7%) developed cutaneous aGVHD. A total of 152 patients (63%) were identified with rash within 1 year after PBSCT. The proportion of patients who experienced peripheral eosinophilia was not different between those with an aGVHD versus non-aGVHD rash (P ≥ .90), nor when stratified by CD34+ selection method (Isolex, P = .70; CliniMACS, P≥ .90). The proportion of patients with pruritus was also not different between those with an aGVHD rash versus non-aGVHD rash (P= .20), or when stratified by CD34+ selection modality (Isolex, P = .20; CliniMACS, P = .50). The most common cause of non-aGVHD rash among those with a clear etiology was drug (39% of Isolex; 26% of CliniMACS). Single drug culprits were identified in 51% of drug rashes. The most commonly reported offending agents included antibiotics, keratinocyte growth factor, chemotherapy, and recombinant glycosylated human IL-7.

Dermatologic Urgencies and Emergencies: What Every Pathologist Should Know

CONTEXT.—

Fatal dermatologic diseases and ones with high morbidity can occur in the inpatient setting. In such cases, prompt and accurate assessment of a bedside skin biopsy is required. This may be challenging for many pathologists who are not familiar with the complexity of skin pathology and skin terminology within the fields of dermatopathology and dermatology.

OBJECTIVE.—

To provide the pathologist with a practical, up-to-date, and "must-know" reference guide on dermatologic urgencies and emergencies from a real-world perspective, highlighting diagnostic pearls, diagnostic pitfalls, and commonly encountered practice gaps. This review will focus on key diseases with which every pathologist should be familiar, including angioinvasive fungal infections, Stevens-Johnson syndrome/toxic epidermal necrolysis, staph-scalded-skin syndrome, acute graft-versus-host disease, bullous pemphigoid, calciphylaxis, Sweet syndrome and its histiocytoid variant, pyoderma gangrenosum, and leukocytoclastic vasculitis, as well as those in their clinical and histopathologic differential.

DATA SOURCES.—

This review is based on peer-reviewed literature and our personal experiences with these diseases at major academic institutions, including one where a large number of stem cell transplants are performed. This review is unique as it represents collaborative expert opinion from both a dermatopathology and a dermatology standpoint.

CONCLUSIONS.—

This review outlines the critical role that the pathologist plays in the outcomes of patients with dermatologic urgencies and emergencies. Improved patient care will result from prompt and accurate histopathologic diagnoses as well as an open line of communication with the dermatologist.

Dermatologic Conditions of the Early Post-Transplant Period in Hematopoietic Stem Cell Transplant Recipients

Hematopoietic stem cell transplants (HSCTs) are used to treat a variety of conditions, including hematologic malignancies, bone marrow failure syndromes, and immunodeficiencies. Over 60,000 HSCTs are performed annually worldwide, and the numbers continue to increase. Indeed, as new conditioning regimens develop, more and more individuals, including those of older age, will be eligible for transplants. Nevertheless, although HSCTs are clearly a life-saving and necessary treatment for thousands of patients per year, there is still substantial morbidity and mortality associated with the procedure. Of note, skin eruptions in the post-HSCT period are frequent and often significantly reduce quality of life in recipients. Moreover, these cutaneous findings sometimes herald an underlying systemic condition, presenting possible opportunities for timelier intervention. Dermatologists therefore play a vital role in distinguishing life-threatening conditions from benign issues and prompting recognition of critical complications earlier in their course. This article aims to review the major dermatologic conditions occurring in the early post-HSCT period.

Markers of systemic involvement and death in hospitalized cancer patients with severe cutaneous adverse reactions

BACKGROUND

Severe cutaneous adverse reactions (SCARs) are frequent in inpatient oncology. Early intervention might reduce morbidity, mortality, and hospitalization costs; however, current clinical and histologic features are unreliable SCAR predictors. There is a need to identify rational markers of SCARs that could lead to effective therapeutic interventions.

OBJECTIVE

To characterize the clinical and serologic features of hospitalized patients with cancer who developed SCARs.

METHODS

Retrospective review of 49 hospitalized cancer patients with a morbilliform rash, recorded testing for serum cytokines (interleukin [IL] 6, IL-10, and tumor necrosis factor [TNF] α) or elafin, and a prior dermatology consultation. Patients were categorized as having a simple morbilliform rash without systemic involvement or complex morbilliform rash with systemic involvement.

RESULTS

Fifteen out of 49 patients (30.6%) were deceased at 6 months from time of dermatologic consultation. Elafin, IL-6, and TNF-α were significantly higher in patients who died compared with patients who were still alive at 6 months. IL-6 and IL-10 were significantly higher in patients with a drug-related complex rash.

LIMITATIONS

Retrospective design, limited sample size, and high-risk patient population.

CONCLUSION

In cancer patients with SCARs, elafin, IL-6, and TNF-α levels might predict a poor outcome. Agents directed against these targets might represent rational treatments for the prevention of fatal SCARs.

Cutaneous Graft-Versus-Host Disease: Diagnosis and Treatment

Graft-versus-host disease (GVHD) is an immunological reaction and a frequent complication following allogeneic hematopoietic stem cell transplantation. It is associated with high mortality rates and may have a significant negative impact on the patient's quality of life, particularly in the chronic-stage setting. Many different organs can be involved, which leads to a wide range of clinical manifestations. In this context, dermatologists play a key role by diagnosing and treating GVHD from the outset since cutaneous features are not just the most common but are also usually the presenting sign. Several skin-direct therapies are available and may be indicated as monotherapy or adjuvant treatment in order to allow faster tapering and withdrawal of systemic immunosuppression. Treatment of steroid-refractory patients remains a challenge and, to date, no consensus has been reached for one single agent in second-line therapy. This article aims to review skin involvement as well as provide and update discussion on therapeutic options for both acute and chronic cutaneous GVHD.

Inflammatory Dermatopathology for General Surgical Pathologists

Owing to the wide variety and complexity of inflammatory skin diseases, inflammatory dermatopathology can be a challenging topic for dermatopathologists and general surgical pathologists alike. Following a basic tissue reaction pattern approach, this article reviews the most common and important entities of each pattern, with emphasis on differential diagnosis, diagnostic pitfalls, and appropriate workup when indicated. A few dermatologic emergencies are also discussed.

Surgical Pathologic Diagnosis

Surgical pathology results can play a crucial role in the management of immunocompromised patients. Here we highlight factors that differ between immunocompromised and immunocompetent hosts, such as variation in inflammatory response. Conditions that are covered include drug reactions, disease within solid organ allografts, immune reconstitution inflammatory syndrome, specific immunodeficiency syndromes, neoplasms related to viral infections, and viral, bacterial, fungal, and parasitic infections. Special techniques including immunohistochemistry, in situ hybridization and molecular detection of pathogen nucleic acid from formalin-fixed, paraffin-embedded tissue are discussed.

Histopathologic Features of Cutaneous Acute Graft-Versus-Host Disease in T-Cell-Depleted Peripheral Blood Stem Cell Transplant Recipients

T-cell-depleted (TCD) allogeneic hematopoietic stem cell transplantation demonstrates similar efficacy and reduced incidence and severity of graft-versus-host disease (GVHD) in appropriately selected patients versus T-cell-replete transplantation. The histopathology of cutaneous acute GVHD (aGVHD) after TCD peripheral blood stem cell transplants (PBSCTs) is not described. We identified 13 cases of patients after TCD PBSCT, with definitive aGVHD, and 20 cases of non-aGVHD skin rash in patients after TCD PBSCT, during multidisciplinary review by a dermatopathologist, dermatologist, and transplant physician, incorporating clinical presentation, therapeutic response, and histopathology data. Histopathologic features of aGVHD and non-aGVHD skin rash in TCD PBSCT patients were compared to each other, and also to features recently reported for non-TCD transplant recipients. aGVHD and non-aGVHD skin rash in TCD PBSCT patients' biopsies had similar rates of epidermal acanthosis, dermal melanophages, neutrophils, plasma cells, eosinophils, and extravasated erythrocytes. While satellitosis, exocytosis and adnexal involvement slightly favored aGVHD, more notable differential findings favoring aGVHD were diffuse (vs. focal/absent) basal vacuolization (77% aGVHD vs. 25% non-aGVHD rash), involvement of the entire epidermis (vs. partial thickness) by necrotic keratinocytes (42% aGVHD vs. 0% non-aGVHD rash), and nondense (rather than exuberant) inflammatory infiltrates (77% vs. 20%). After filtering features seen in all TCD samples (epidermal acanthosis, dermal melanophages, neutrophils, plasma cells, eosinophils, and extravasated erythrocytes), the most distinct features belonging to aGVHD-positive TCD samples were diffuse basal vacuolization, slight rather than dense inflammatory infiltrates, and necrotic keratinocytes involving the entire epidermis. Awareness of these features may help when evaluating a skin rash occurring after a TCD transplant.

A review of important skin disorders occurring in the posttransplantation patient

Hematopoietic stem cell transplantation continues to be the mainstay of treatment for many hematologic dyscrasias and malignancies, including acute leukemias, lymphomas, and aplastic anemia. There can be significant complications, however, and often these complications are manifested in the skin as an eruption. Common among these are acute and chronic graft-versus-host disease, erythema multiforme, Stevens-Johnson syndrome/toxic epidermal necrolysis, eruption of lymphocyte recovery, staphylococcal scalded skin syndrome, morbiliform drug eruptions, infections, and toxic erythema of chemotherapy. These entities can show significant clinical and histopathologic overlap, yet accurate distinctions among them are critical to initiating appropriate clinical interventions. In this review, we will discuss the key clinical and histopathologic findings in each entity as well as appropriate differential diagnostic entities.

Eosinophils in the blood of hematopoietic stem cell transplanted patients are activated and have different molecular marker profiles in acute and chronic graft-versus-host disease

While increased numbers of eosinophils may be detected in patients with graft-versus-host disease (GVHD) following hematopoietic stem cell transplantation, it is not known if eosinophils play a role in GVHD. The aims of this study were to determine: whether eosinophils are activated during GVHD; whether the patterns of activation are similar in acute and chronic GVHD; and the ways in which systemic corticosteroids affect eosinophils. Transplanted patients (n = 35) were investigated for eosinophil numbers and the expression levels of 16 eosinophilic cell surface markers using flow cytometry; all the eosinophil data were analyzed by the multivariate method OPLS-DA. Different patterns of molecule expression were observed on the eosinophils from patients with acute, chronic, and no GVHD, respectively. The molecules that provided the best discrimination between acute and chronic GVHD were: the activation marker CD9; adhesion molecules CD11c and CD18; chemokine receptor CCR3; and prostaglandin receptor CRTH2. Patients with acute or chronic GVHD who received systemic corticosteroid treatment showed down-regulation of the cell surface markers on their eosinophils, whereas corticosteroid treatment had no effect on the eosinophil phenotype in the patients without GVHD. In summary, eosinophils are activated in GVHD, display different activation profiles in acute and chronic GVHD, and are highly responsive to systemic corticosteroids.

Fluorescence in situ hybridization (FISH) as an aid for the diagnosis of graft-versus-host disease in two multivisceral organ transplant patients

We herein describe 2 cases of adult multivisceral transplant patients who developed graft-versus-host disease manifesting predominantly as lichenoid skin papules and plaques. The diagnosis was supported by histopathology but ultimately corroborated by the utilization of the fluorescence in situ hybridization (FISH) technique using X and Y chromosome probes on unstained biopsy slides. In both cases, FISH revealed a high percentage of donor-derived cells as part of the inflammatory infiltrate in the skin biopsy. This report adds to the previous publications showing the utility of FISH in corroborating the diagnosis of graft-versus-host disease in transplant patients with unmatched sex donor.

Workshop report from the National Institutes of Health Taskforce on the Research Needs of Eosinophil-Associated Diseases (TREAD)

BACKGROUND

Eosinophils are blood cells that are often found in high numbers in the tissues of allergic conditions and helminthic parasite infections. The pathophysiologic roles that eosinophils may serve in other human "eosinophil-associated" diseases remain obscure.

OBJECTIVE

National Institutes of Health (NIH) Institutes and the Office of Disease Prevention assembled an international taskforce of clinical and basic scientists with the charge to propose and prioritize unmet research needs in eosinophil-associated diseases.

METHODS

The taskforce used an organ system approach to identify the different and common themes of eosinophil cell involvement in these diseases. In early 2012, a draft document was circulated for review. The document was amended and the prioritizations were set at a NIH-organized workshop in June 2012.

RESULTS

The taskforce identified significant research needs. These needs cross disease entities but some are disease specific. There are substantial shortcomings to the various preclinical animal models, as well as significant gaps in our epidemiologic, pathophysiologic, diagnostic, prognostic, and therapeutic knowledge. The taskforce recognized that recent efforts by patient advocacy groups have played instrumental roles in improving the identification and characterization of these disorders. However, communications among the eosinophil-interested communities, for example, governmental funding and regulatory agencies, and industry and clinician scientists need to be more comprehensive.

CONCLUSIONS

Significant efforts are required to address our knowledge gaps to improve the outcomes of eosinophil-associated diseases. NIH Institutes, other federal agencies, lay organizations, and the pharmaceutical industry should consider the taskforce's recommendations in their future research activities.

Current knowledge in inflammatory dermatopathology

The complex and fascinating spectrum of inflammatory skin disease, and the comprehension of it, is ever expanding and evolving. During the first decade of the 21st century, numerous advances in the understanding of inflammatory disease mechanisms have occurred, particularly in psoriasis and atopic dermatitis. Continuation of this trend will assure a future in which molecular tests for biomarkers of immediate clinical relevance are used in routine patient care, not only for diagnosis but also for prognosis and management. This article focuses on selected recent or noteworthy developments that are clinically relevant for the histologic diagnosis of inflammatory skin diseases.

Assessment of the 'no eosinophils' rule: are eosinophils truly absent in pityriasis lichenoides, connective tissue disease, and graft-vs.-host disease?

Eosinophils are often present in the inflammatory infiltrate of an interface dermatitis, but the diagnostic specificity of eosinophils in interface dermatitis has not been formally evaluated. We retrospectively identified 97 examples of interface dermatitis with clinically confirmed diagnoses, including lupus erythematosus (LE), lichen planus, pityriasis lichenoides (PL), graft-vs.-host disease (GVHD), dermatomyositis (DM) and drug reaction. Diagnoses were clinically confirmed by at least two dermatologists. Slides were reviewed in a blinded fashion by at least two dermatopathologists. The average eosinophil count per 10 ×200 (×20 objective) fields was lowest for PL (0.2), DM (0.3), GVHD (0.4), and LE (0.5) [defined as Group 1] and was higher for lichen planus, drug reactions, erythema multiforme (major and minor) and viral exanthems [defined as Group 2]. Distinction between Group 1 and Group 2 was maximized using an eosinophil count cutoff of 1.1. In conclusion, eosinophils are usually rare to absent in PL, DM, most forms of LE and GVHD. While final interpretation requires a composite assessment of all features, our results suggest that the presence of even a single eosinophil within nine or ten ×20 fields argues against a diagnosis of PL, DM or LE.

Graft-versus-host disease: part I. Pathogenesis and clinical manifestations of graft-versus-host disease

Approximately 25,000 allogeneic hematopoietic cell transplants are performed worldwide each year for a variety of malignant and non-malignant conditions. Graft-versus-host disease represents one of the most frequent complications and is a major source of long-term morbidity and mortality. Whereas acute graft-versus-host disease is induced by recognition of host tissues as foreign by immunocompetent donor cells, the pathogenesis of chronic graft-versus-host disease is not as well understood, and continues to be a major treatment challenge. Part I of this two-part series reviews the epidemiologic factors, classification, pathogenesis, and clinical manifestations of acute and chronic graft-versus-host disease. Part II discusses the topical, physical, and systemic treatment options available to patients with graft-versus-host disease.