Plaza, Jose Antonio

Lymphomatoid papulosis (LyP) has several histopathologic presentations. LyP featuring gamma-delta (γδ) T-cell receptor expression may masquerade as and may be misdiagnosed as aggressive cutaneous T-cell lymphoma, particularly primary cutaneous γδ T-cell lymphoma (PCGDTL) or γδ mycosis fungoides. We performed a clinicopathologic analysis of the largest series of LyP featuring γδ T-cell expression. We identified 26 patients with a diagnosis of LyP with γδ T cells from our institutions, as well as through a comprehensive review of the literature, and characterized these cases. Most cases were treated with topical steroids or not treated at all. The majority of cases showed a CD4-CD8+ phenotype and featured at least one cytotoxic marker. Histopathologic features included an intraepidermal or dermal infiltrate with large cells and frequent angiotropism. One case was initially misdiagnosed as PCGDTL, requiring further therapy. Our case series, the largest international cohort of γδ T cell predominant LyP cases, confirms marked clinicopathologic heterogeneity that may contribute to misdiagnosis, reasserting the need to identify classic clinical features, CD30+ T-cell components, and markers of cytotoxicity when dealing with this differential diagnosis. A limitation of this study includes somewhat limited follow-up, histologic, and immunophenotypic information for some cases.

AbstractBackgroundAppropriate 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.MethodsRAND/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.ResultsFor 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.ConclusionsAUC 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.

BackgroundAppropriate use criteria (AUC) provide physicians guidance in test selection, and can affect health care delivery, reimbursement policy and physician decision‐making.ObjectivesThe American Society of Dermatopathology, with input from the American Academy of Dermatology and the College of American Pathologists, sought to develop AUC in dermatopathology.MethodsThe RAND/UCLA appropriateness methodology, which combines evidence‐based medicine, clinical experience and expert judgment, was used to develop AUC in dermatopathology.ResultsWith 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,” 52 (25%) “rarely appropriate” and 43 (20%) “uncertain appropriateness.”LimitationsThe methodology requires a focus on appropriateness without comparison between tests and irrespective of cost.ConclusionsThe ultimate decision of when to order specific test rests with the physician and is one where the expected benefit exceeds the negative consequences. This publication outlines the recommendations of appropriateness—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.

Lymphomatoid papulosis (LyP) and cutaneous anaplastic large cell lymphoma (ALCL) belong to the spectrum of cutaneous CD30+ lymphoproliferative disorders, an indolent form of T‐cell lymphoproliferative disease. We reviewed 21 cases of CD30+ lymphoproliferative lesions expressing cytotoxic profile (CD8+). Seven cases of cutaneous ALCL, 2 cases of systemic ALCL involving the skin, and 12 cases of LyP. The cases of LyP were predominated by small lymphocytes exhibiting a prominent epidermotropic pattern consistent with either type B or type D LyP. Four cases showed co‐expression of CD56. The ALCL cases included myxoid features, pseudoepitheliomatous change, and an intravascular component. In all cases that were primary in the skin an indolent clinical course was seen while one patient with systemic myxoid ALCL is in remission following systemic multiagent chemotherapy. The paucity of other neutrophils and eosinophils and concomitant granulomatous inflammation were distinctive features in cases of type B and type D LyP. CD30 and CD45 Ro positivity and a clinical course typical of LyP were useful differentiating features from an aggressive cytotoxic CD8+ T cell lymphoma. In all cases that were primary in the skin an indolent clinical course was observed. CD30 and CD45 Ro positivity and a clinical course typical of LyP were useful in preventing a misdiagnosis of an aggressive cytotoxic CD8+ T cell lymphoma.