Eosinophils in psoriasis: A systematic review and meta-analysis introducing a study quality assessment tool for diagnostic pathology studies

BACKGROUND

The histopathologic features of psoriasis are well-documented, but recent studies have highlighted atypical features, such as eosinophils, in clinically confirmed cases.

METHODS

A systematic review exploring eosinophils in psoriasis was performed. A novel quality assessment tool (SQAT-Path) we designed for cross-sectional pathology studies was employed.

RESULTS

Five studies (N = 218) were identified. The pooled prevalence of dermal eosinophils in psoriasis was 46% (95% confidence interval, 0.27-0.66). The prevalences of 1 to 5 lesional eosinophils (24%) compared to >5 eosinophils (26%) were similar. There was no association between eosinophils and prior treatment. There was also no association between eosinophils and spongiosis. In SQAT-Path, studies scored between 9 and 18 (out of a maximum of 27: "fair" to "good"), consistent with the ratings using other assessment tools.

CONCLUSION

Eosinophils were found in approximately half of systematically studied and published cases of psoriasis. When present, their quantity is variable, with the likelihood of having greater than 5 eosinophils in a biopsy section comparable to having between 1 and 5. Greater than 5 eosinophils, as an isolated finding, would not be typical of psoriasis, but should not preclude its diagnosis without considering the overall histologic context.

Comparison of S100A8 and PRAME as biomarkers for distinguishing melanoma from melanocytic naevus: a case-control analysis

BACKGROUND

S100A8 is a melanoma biomarker expressed in the melanoma-associated epidermal keratinocytes, but its diagnostic utility has not been compared with other biomarkers, including PRAME.

OBJECTIVES

To compare the utility of S100A8 and PRAME immunohistochemistry (IHC) in the differential diagnosis of melanoma and naevi in a case-control study.

METHODS

A previously described cohort of 209 melanomas (case samples) and naevi (control samples) dual-immunostained for S100A8 and PRAME were included. For S100A8, previously reported scores indicating the proportion of tumour-associated epidermis stained (0 = indeterminate; 1 = 0-4%; 2 = 5-25%; 3 = 26-50%; 4 = 51-75%; 5 = > 75%) were utilized. PRAME IHC was reviewed by at least two reviewers and a consensus score assigned, with score indicating the proportion of tumour stained (0 = indeterminate; 1 = 0%; 2 = 1-50%; 3 = > 50%). A positive test was defined as > 50% staining.

RESULTS

The area under the receiver operating characteristic curves for S100A8 (0.833) and PRAME (0.874) were not significantly different from each other (P = 0.22). The diagnostic sensitivity and specificity were 42.4% [95% confidence interval (CI) 32.6-52.8%] and 98.2% (95% CI 93.6-99.8%) for S100A8, and 79.8% (95% CI 70.5-87.2%) and 87.3% (95% CI 79.6-92.9%) for PRAME, respectively. A combined test requiring both S100A8 and PRAME IHC positivity had a sensitivity of 39.4% (95% CI 29.7-49.7%) and specificity of 99.1% (95% CI 95.0-100.0%).

CONCLUSIONS

S100A8 and PRAME have utility in the diagnostic workup of melanoma, with S100A8 being more specific and PRAME being more sensitive when using this threshold. Our findings suggest that these two immunohistochemical markers may favourably complement one another to improve the detection of melanoma.

Localized calcium oxalate crystals in primary cutaneous aspergillosis

Select Aspergillus species can produce oxalate as a fermentation byproduct, which may react with calcium ions to produce insoluble calcium oxalate crystals in tissues. These crystals are frequently associated with pulmonary Aspergillus infections, yet are rarely described in primary cutaneous aspergillosis. Herein, we report the presence of calcium oxalate crystals detected on cutaneous specimens from primary cutaneous Aspergillus niger and Aspergillus fumigatus infections in an immunocompromised, premature infant. No metabolic sources of oxalosis were found.

The Free Sign in morphea and other sclerosing disorders: A clue to the presence of early sclerosis?

BACKGROUND

The Floating Sign is a histopathologic clue to the diagnosis of autoimmune sclerosing skin disorders such as morphea and interstitial granulomatous dermatitis (IGD). On the other hand, the "free-floating" sign has been associated with neoplasms, for example, dermatofibroma and interstitial mycosis fungoides. Herein, we report the Free Sign in sclerosing skin disorders.

METHODS

In a case-control study, we applied detailed histopathologic definitions of Floating Sign and Free Sign to assess their presence in morphea, IGD, and other sclerosing disorders.

RESULTS

Free Sign was present in most cases of morphea (46/55, 84%) and IGD (7/13, 54%) but not necrobiosis lipoidica (NL) (6/14, 42.8%) or sclerodermoid graft versus host disease (SGVHD) (2/7, 28.5%). The sensitivity and specificity of Free Sign for morphea versus other disorders was 84% and 56%, respectively. Floating Sign was not identified in most cases: NL (3/14, 21.4%), SGVHD (1/7, 14.2%), morphea (5/55, 9%), IGD (1/13, 7.7%). The diagnostic sensitivity of Floating Sign in morphea was 9%.

CONCLUSIONS

The Free Sign was present in most cases of morphea in our series and may represent a clue to the presence of evolving sclerosis. Free Sign may be seen in other sclerosing disorders. Technical artifact is a potential cause of a false-positive Free Sign.

When a travel bug gets you down: severe, hypotensive African tick bite fever and response to therapy

African tick bite fever, resulting from Rickettsia africae inoculation, is endemic in sub-Saharan Africa. We present a United States traveler with African tick bite fever 5 days after she returned from a mission trip to Zimbabwe. The patient exhibited symptomatic hypotension in addition to more typical findings, including fever, fatigue, and a necrotic eschar. The diagnosis was supported by histopathological findings and the patient's symptoms rapidly resolved with oral doxycycline therapy. We believe this case represents the first African tick bite fever diagnosis associated with symptomatic hypotension. This case additionally serves as a reminder of the importance of evaluating patient travel history.

Localized alopecic myxedema of the scalp

Myxedema is a rare, cutaneous complication of autoimmune thyroid diseases that most often affects the anterior shins. Herein, we report a patient with a history of Graves disease and Hashimoto thyroiditis who presented with boggy, alopecic patches associated with scalp pruritus. Punch biopsies from these lesions showed increased interstitial mucin in the reticular dermis, consistent with localized myxedema. This report showcases a rare presentation of localized myxedema of the scalp, highlighting the diverse cutaneous manifestations of autoimmune thyroid diseases.

Case report: Mounded and refractory keratoses (MARK), a novel presentation of pemphigus vulgaris

Pemphigus vulgaris (PV) is a rare immunobullous disease. Although it classically presents as generalized flaccid blisters affecting the skin and mucosae, atypical cases of PV can be diagnostically challenging. Herein, we report an underrecognized non-blistering manifestation of pemphigus vulgaris, which we call mounded and refractory keratoses (MARK). MARK presents as exuberant scaling plaques on the scalp, often in the skin of color. When MARK features are present, pemphigus vulgaris is prone to misdiagnosis, clinically and histopathologically, leading to delays in appropriate treatment. Specifically, biopsies from these patients may resemble acantholytic dyskeratosis, resulting in initial misdiagnosis. Thus, recognizing this presentation may aid physicians in diagnosing and monitoring the recurrence of pemphigus vulgaris.

Trichodysplasia spinulosa: a presentation of polyomavirus infection in immunosuppressed patients

Trichodysplasia spinulosa (TS) is a rare skin condition that occurs mainly in immunosuppressed patients. Although initially postulated to be an adverse effect of immunosuppressants, TS-associated polyomavirus (TSPyV) has since been isolated from TS lesions and is now considered to be the causative agent. Trichodysplasia spinulosa presents with folliculocentric papules with protruding keratin spines, most commonly on the central face. Trichodysplasia spinulosa can be diagnosed clinically, but the diagnosis can be confirmed with histopathological examination. Histological findings include the presence of hyperproliferating inner root sheath cells containing large eosinophilic trichohyaline granules. Polymerase chain reaction (PCR) can also be used to detect and quantify TSPyV viral load. Owing to the paucity of reports in the literature, TS is frequently misdiagnosed and there is no high-quality evidence to guide management. Herein, we present a renal transplant recipient with TS that did not respond to topical imiquimod but improved upon treatment with valganciclovir and reduction of the mycophenolate mofetil dose. Our case highlights the inverse relationship between immune status and disease progression in this condition.

Appropriate use criteria for ancillary diagnostic testing in dermatopathology: New recommendations for 11 tests and 220 clinical scenarios from the American Society of Dermatopathology Appropriate Use Criteria Committee

BACKGROUND

Appropriate use criteria (AUC) provide patient-centered physician guidance in test selection. An initial set of AUC was reported by the American Society of Dermatopathology (ASDP) in 2018. AUC reflect evidence collected at single timepoints and may be affected by evolving evidence and experience. The objective of this study was to update and expand AUC for selected tests.

METHODS

RAND/UCLA (RAND Corporation [Santa Monica, CA]/University of California Los Angeles) methodology used includes the following: (a) literature review; (b) review of previously rated tests and previously employed clinical scenarios; (c) selection of previously rated tests for new ratings; (d) development of new clinical scenarios; (e) selection of additional tests; (f) three rating rounds with feedback and group discussion after rounds 1 and 2.

RESULTS

For 220 clinical scenarios comprising lymphoproliferative (light chain clonality), melanocytic (comparative genomic hybridization, fluorescence in situ hybridization, reverse transcription polymerase chain reaction, telomerase reverse transcriptase promoter), vascular disorders (MYC), and inflammatory dermatoses (periodic acid-Schiff, Gömöri methenamine silver), consensus by panel raters was reached in 172 of 220 (78%) scenarios, with 103 of 148 (70%) rated "usually appropriate" or "rarely appropriate" and 45 of 148 (30%), "appropriateness uncertain."

LIMITATIONS

The study design only measures appropriateness. Cost, availability, test comparison, and additional clinical considerations are not measured. The possibility that the findings of this study may be influenced by the inherent biases of the dermatopathologists involved in the study cannot be excluded.

CONCLUSIONS

AUC are reported for selected diagnostic tests in clinical scenarios that occur in dermatopathology practice. Adhering to AUC may reduce inappropriate test utilization and improve healthcare delivery.

Immune profiling of lupus miliaris disseminatus faciei and successful management with anti-tumour necrosis factor therapy

Lupus miliaris disseminatus faciei (LMDF) is a chronic inflammatory dermatosis of unknown aetiology, most often seen in young adults. Although many treatments for LMDF exist, treatment guidelines have not been developed, and response to therapy is generally unpredictable. We present the results of transcriptomic analysis of LMDF lesional skin, which revealed a variety of differentially expressed genes linking LMDF to alterations in innate and adaptive T helper 1 immunity. Immunohistochemical analysis was also performed, identifying similar changes in T-cell immune responses. Given evidence for increased tumour necrosis factor (TNF) pathway activity, our patient, who had previously been refractory to multiple treatments, was initiated on TNF inhibitor therapy with excellent response. This characterization of the LMDF immune response may lead to improved treatment of this condition.

Orf progressiva: giant progressive and destructive infections in the immunocompromised

Orf virus causes a self-limited infection in humans that resolves without scarring within 6-12 weeks. However, lesions in the immunocompromised can be progressive and disfiguring. The lesions frequently recur after treatment. To our knowledge, there are eleven published cases of these infections. We propose the name orf progressiva to call attention to this progressive, treatment-resistant entity. We present a 43-year-old male ranch owner with a history of renal transplantation who contracted an orf infection from his lamb. The infection recurred despite attempts at debridement, but achieved near complete resolution after treatment with imiquimod and valacyclovir. The histologic findings of orf progressiva are identical to the early stages of classic orf infection and are characterized by epithelial hyperplasia, intracytoplasmic eosinophilic inclusions, and an edematous, vascular dermis. There is no standard treatment for orf progressiva. Surgical excision has frequently resulted in rapid reoccurrence. Topical therapies such as imiquimod and cidofovir cream in combination with excision have been successful in some cases. Acyclovir or valacyclovir with imiquimod has been reported to be effective. Two patients achieved cure with imiquimod alone. We summarize these cases to prompt recognition of orf progressiva as a distinct clinical entity that requires treatment.

Granuloma annulare-like eruption in chronic lymphocytic leukemia

We report a patient with new-onset ulcerated granuloma annulare with concomitant involvement of B-cell leukemia. A granuloma annulare-like eruption with concomitant B cell chronic lymphocytic leukemia involvement in the skin is extremely rare, as only three cases have been previously reported in the literature to our knowledge. Given the rarity of ulceration in conventional granuloma annulare, it is possible this finding may serve as a diagnostic clue for underlying malignancy.

TERT and TERT promoter in melanocytic neoplasms: Current concepts in pathogenesis, diagnosis, and prognosis

BACKGROUND AND OBJECTIVE

Located on chromosome locus 5p15.33, telomerase reverse transcriptase (TERT or hTERT) encodes the catalytic subunit of telomerase which permits lengthening and preservation of telomeres following mitosis. Mutations in TERT promoter (TERT-p) upregulate expression of TERT, allowing survival of malignant cells and tumor progression in wide variety of malignancies including melanoma. The objective of this review is to examine the roles of TERT and TERT-p in the pathogenesis, diagnosis, and prognostication of cutaneous melanoma.

METHODS

All studies of TERT or TERT-p in cutaneous melanocytic neoplasms with the following inclusion criteria were reviewed: publication date between 2010 and 2019, English language, and series of ≥3 cases were reviewed for evidence supporting the role of TERT in pathogenesis, diagnosis, and prognosis. Studies with <3 cases or focused primarily on mucosal or uveal melanocytic tumors were excluded.

RESULTS AND CONCLUSION

TERT-p mutations are frequent in chronic and non-chronic sun damage melanoma and correlate with adverse prognosis, inform pathogenesis, and may provide diagnostic support. While TERT-p mutations are uncommon in acral melanoma, TERT copy number gains and gene amplification predict reduced survival. Among atypical spitzoid neoplasms, TERT-p mutations identify biologically aggressive tumors and support the diagnosis of spitzoid melanoma. TERT-p methylation may have prognostic value in pediatric conventional melanoma and drive tumorigenesis in melanoma arising within congenital nevi. Finally, TERT-p mutations may aid in the differentiation of recurrent nevi from recurrent melanoma.

Pink verrucous plaque in a man with systemic mastocytosis

Porokeratosis ptychotropica is a rare and commonly misdiagnosed subtype of porokeratosis involving the body folds. We present a 53-year-old man with systemic mastocytosis who presented with a pruritic, verrucous plaque in the gluteal fold that showed multiple cornoid lamellae on histopathologic evaluation, diagnostic of porokeratosis ptychotropica. Various treatments have been reported, including topical corticosteroids, retinoids, vitamin D analogs, calcineurin inhibitors, imiquimod, phototherapy, cryotherapy, or ablative laser therapy, but recurrences are common.

Long-term Western diet intake leads to dysregulated bile acid signaling and dermatitis with Th2 and Th17 pathway features in mice

BACKGROUND

Dietary interventions are implicated in the development of atopic dermatitis, psoriasis, and acne.

OBJECTIVE

To investigate the effect of diet and the bile acid (BA) receptors, such as TGR5 (Takeda G protein receptor 5) and S1PR2 (sphingosine-1-phosphate receptor 2) in the development of dermatitis.

METHODS

C57BL/6 mice were fed a control diet (CD) or Western diet (WD) since weaning until they were 10 months old followed by analyzing histology, gene expression, and BA profiling.

RESULTS

Mice developed dermatitis as they aged and the incidence was higher in females than males. Additionally, WD intake substantially increased the incidence of dermatitis. Cutaneous antimicrobial peptide genesS100A8, S100A9, and Defb4 were reduced in WD-fed mice, but increased when mice developed skin lesions. In addition, Tgr5 and TGR5-regulated Dio2 and Nos3 were reduced in WD intake but induced in dermatitic lesions. Trpa1 and Trpv1, which mediate itch, were also increased in dermatitic lesions. The expression of S1pr2 and genes encoding sphingosine kinases, S1P phosphatases, binding protein, and transporter were all reduced by WD intake but elevated in dermatitic lesions. Furthermore, dermatitis development increased total cutaneous BA with an altered profile, which may change TGR5 and S1PR2 activity. Moreover, supplementation with BA sequestrant cholestyramine reduced epidermal thickening as well as cutaneous inflammatory cytokines.

CONCLUSION

In summary, activation of TGR5 and S1PR2, which regulate itch, keratinocyte proliferation, metabolism, and inflammation, may contribute to WD-exacerbated dermatitis with Th2 and Th17 features. In addition, elevated total BA play a significant role in inducing dermatitis and cutaneous inflammation.

Recurrent retroauricular cystic nodules: lichen planus follicularis tumidus

Lichen planus follicularis tumidus (LPFT) is a rare subtype of lichen planus (LP) that has been most commonly described in middle-aged women. LPFT clinically manifests as recurrent cystic follicular nodules that preferentially involve the retroauricular area; concurrent classic LP lesions on the extremities and mucosal surfaces may also be present. Histologically, LPFT demonstrates epithelial-lined follicular cysts filled with orthokeratotic keratin surrounded by a dense lichenoid infiltrate. We present a case of a 67-year-old man with clinical and histopathologic findings consistent with LPFT and discuss differential diagnostic considerations for entities resembling LPFT. Lastly, treatment options for LPFT are reviewed.

Microscopy with ultraviolet surface excitation (MUSE): A novel approach to real-time inexpensive slide-free dermatopathology

Traditional histology relies on processing and physically sectioning either frozen or formalin-fixed paraffin-embedded (FFPE) tissue into thin slices (typically 4-6 μm) prior to staining and viewing on a standard wide-field microscope. Microscopy using ultraviolet (UV) surface excitation (MUSE) represents a novel alternative microscopy method that works with UV excitation using oblique cis-illumination, which can generate high-quality images from the cut surface of fresh or fixed tissue after brief staining, with no requirement for fixation, embedding and histological sectioning of tissue specimens. We examined its potential utility in dermatopathology. Concordance between MUSE images and hematoxylin and eosin (H&E) slides was assessed by the scoring of MUSE images on their suitability for identifying 10 selected epidermal and dermal structures obtained from minimally fixed tissue, including stratum corneum, stratum granulosum, stratum spinosum, stratum basale, nerve, vasculature, collagen and elastin, sweat glands, adipose tissue and inflammatory cells, as well as 4 cases of basal cell carcinoma and 1 case of pseudoxanthoma elasticum deparaffinized out of histology blocks. Our results indicate that MUSE can identify nearly all normal skin structures seen on routine H&E as well as some histopathologic features, and appears promising as a fast, reliable and cost-effective diagnostic approach in dermatopathology.

Acquired bullous acrodermatitis enteropathica as a histologic mimic of pemphigus foliaceus in a patient on parenteral nutrition

The original article was published on July19, 2017 and corrected on May 15, 2018. The revised version of the article includes a funding source for Dr. Maija Kiuru's participation in this case report, awarded by the National Cancer Institute, National Institutes of Health grant K12CA138464. This change appears in the revised online PDF copy of this article.

Appropriate use criteria in dermatopathology: Initial recommendations from the American Society of Dermatopathology

BACKGROUND

Appropriate use criteria (AUC) provide physicians guidance in test selection, and can affect health care delivery, reimbursement policy, and physician decision-making.

OBJECTIVES

The American Society of Dermatopathology, with input from the American Academy of Dermatology and the College of American Pathologists, sought to develop AUC in dermatopathology.

METHODS

The RAND/UCLA appropriateness methodology, which combines evidence-based medicine, clinical experience, and expert judgment, was used to develop AUC in dermatopathology.

RESULTS

With the number of ratings predetermined at 3, AUC were developed for 211 clinical scenarios involving 12 ancillary studies. Consensus was reached for 188 (89%) clinical scenarios, with 93 (44%) considered "usually appropriate" and 52 (25%) "rarely appropriate" and 43 (20%) having "uncertain appropriateness."

LIMITATIONS

The methodology requires a focus on appropriateness without comparison between tests and irrespective of cost.

CONCLUSIONS

The ultimate decision to order specific tests rests with the physician and is one where the expected benefit exceeds the negative consequences. This publication outlines the recommendations of appropriateness-the AUC for 12 tests used in dermatopathology. Importantly, these recommendations may change considering new evidence. Results deemed "uncertain appropriateness" and where consensus was not reached may benefit from further research.

Debilitating erosive lichenoid interface dermatitis from checkpoint inhibitor therapy

As the list of anti-tumor immunotherapy agents and the list of cancers treated by these novel agents grow, a subset of patients are experiencing immune-related adverse events as a result of prolonged stimulation of the immune system. Many different immune related adverse events including colitis, hepatitis, pneumonitis, thyroiditis, hypophysitis, and cutaneous reactions can result from blocking these inhibitory pathways. The full spectrum of cutaneous immune related adverse events secondary to checkpoint inhibitor therapy is still being defined. The reported varied presentations include lichenoid reactions and bullous pemphigoid, amongst others. We present a severe cutaneous reaction, a case of debilitating erosive lichenoid dermatitis. This case emphasizes both the wide range of possible cutaneous reactions and the potential severity of these reactions.

Generalized fixed drug eruption to piperacillin/tazobactam and review of literature

Fixed drug eruption (FDE) is an adverse drug reaction characterized by the development of well-circumscribed, round, dusky erythematous macules and plaques on cutaneous or mucosal surfaces. The reaction occurs on the same mucosal or cutaneous site with subsequent exposures to the offending drug. Although FDE usually manifests as a single lesion, in rare instances, more than one lesion may arise and this is referred to as a generalized eruption. Herein, we present a 31year-old man with history of cystic fibrosis who developed a generalized fixed drug eruption to piperacillin/tazobactam (Zosyn, Pfizer). We discuss our patient's course and review causes and outcomes of generalized fixed drug eruptions in the literature.

Improving classification of melanocytic nevi: Association of BRAF V600E expression with distinct histomorphologic features

BACKGROUND

A subset of melanomas carrying a B-Raf proto-oncogene, serine/threonine kinase gene (BRAF) V600E mutation, which is the most common targetable mutation in melanoma, arise in association with a melanocytic nevus that is also harboring a BRAF V600E mutation. The detailed histomorphologic characteristics of nevi positive for BRAF V600E have not been systematically documented.

OBJECTIVE

To identify histomorphologic features correlating with BRAF V600E status in nevi.

METHODS

We retrospectively identified melanocytic nevi from our laboratory reporting system. We performed a histomorphologic analysis and analysis of BRAF V600E expression by immunohistochemistry.

RESULTS

Thirteen nevi (14.8%) were negative and 76 (86.4%) were positive for BRAF V600E. The nevi positive for BRAF V600E were predominantly dermal (predominantly dermal growth in 55.3% of nevi positive for BRAF V600E and 15.4% of nevi negative for BRAF V600E [P = .01]) and showed a congenital growth pattern (congenital growth pattern in 51.3% of nevi positive for BRAF V600E and 15.4% of nevi negative for BRAF V600E [P = .02]). Compared with nevi negative for BRAF V600E, those that were positive for BRAF V600E often exhibited predominantly nested intraepidermal melanocytes, larger junctional nests, abrupt lateral circumscription, and larger cell size. Architectural disorder and inflammatory infiltrates were seen more often in nevi negative for BRAF V600E. BRAF sequencing of a subset of nevi confirmed the immunohistochemical results.

LIMITATIONS

Limitations include the study's retrospective design and the small sample size of nevi negative for BRAF V600E.

CONCLUSIONS

BRAF V600E is associated with distinct histomorphologic features in nevi. These features may contribute to improving the accuracy of classification and diagnosis of melanocytic neoplasms.

Diagnostic Criteria of Ulcerative Pyoderma Gangrenosum: A Delphi Consensus of International Experts

Importance

Pyoderma gangrenosum is a rare inflammatory skin condition that is difficult to diagnose. Currently, it is a "diagnosis of exclusion," a definition not compatible with clinical decision making or inclusion for clinical trials.

Objective

To propose and validate diagnostic criteria for ulcerative pyoderma gangrenosum.

Evidence Review

Diagnostic criteria were created following a Delphi consensus exercise using the RAND/UCLA Appropriateness Method. The criteria were validated against peer-reviewed established cases of pyoderma gangrenosum and mimickers using k-fold cross-validation with methods of multiple imputation.

Findings

Delphi exercise yielded 1 major criterion-biopsy of ulcer edge demonstrating neutrophilic infiltrate-and 8 minor criteria: (1) exclusion of infection; (2) pathergy; (3) history of inflammatory bowel disease or inflammatory arthritis; (4) history of papule, pustule, or vesicle ulcerating within 4 days of appearing; (5) peripheral erythema, undermining border, and tenderness at ulceration site; (6) multiple ulcerations, at least 1 on an anterior lower leg; (7) cribriform or "wrinkled paper" scar(s) at healed ulcer sites; and (8) decreased ulcer size within 1 month of initiating immunosuppressive medication(s). Receiver operating characteristic analysis revealed that 4 of 8 minor criteria maximized discrimination, yielding sensitivity and specificity of 86% and 90%, respectively.

Conclusions and Relevance

This Delphi exercise produced 1 major criterion and 8 minor criteria for the diagnosis of ulcerative pyoderma gangrenosum. The criteria may serve as a guideline for clinicians, allowing for fewer misdiagnoses and improved patient selection for clinical trials.

Classic Ulcerative Pyoderma Gangrenosum Is a T Cell-Mediated Disease Targeting Follicular Adnexal Structures: A Hypothesis Based on Molecular and Clinicopathologic Studies

Background

Pyoderma gangrenosum (PG) is a debilitating ulcerative skin disease that is one of the most common associated diseases seen in patients with inflammatory bowel disease and rheumatoid arthritis. Although PG is classified as a neutrophilic dermatosis, its pathophysiology is poorly understood.

Objective

Use data obtained from patient-reported histories, immunohistochemistry, and gene expression analysis to formulate a hypothesis on PG pathophysiology.

Methods

Ten PG patients participated and answered questions about new ulcer formation. Skin biopsies of healed prior ulcers and adjacent normal skin were obtained from four patients for immunohistochemistry. Scars from healthy patients and patients with discoid lupus were used as additional controls. New onset PG papules were analyzed using immunohistochemistry and gene expression analysis via quantitative real-time PCR.

Results

All PG patients reported that healed sites of previous ulceration are refractory to re-ulceration. Simultaneous biopsies of healed and uninvolved skin triggered ulceration only in the latter. On immunohistochemistry, healed PG scars showed complete loss of pilosebaceous units, which were present in normal skin, and to a lesser extent in control scars, and discoid scars. Early PG papules showed perivascular and peripilosebaceous T cell infiltrates, rather than neutrophils. These early inflammatory events were dominated by increased gene expression of CXCL9, CXCL10, CXCL11, IL-8, IL-17, IFNG, and IL-36G and transcription factors consistent with Th1 phenotype.

Limitations

Small sample size was the main limitation.

Conclusion

We put forth the hypothesis that PG is a T cell response resulting in the destruction of pilosebaceous units.