African tick bite fever (ATBF) is a rickettsial infection that should be considered as the cause of fever in travelers returning from endemic regions of sub-Saharan Africa or the Caribbean. Patients typically present with a flu-like syndrome and may demonstrate one or more cutaneous inoculation eschars as a diagnostic key. We present a case of ATBF in a pregnant woman following her trip to Swaziland. Her symptoms rapidly improved with institution of effective antimicrobial treatment with azithromycin and rifampin; she made a full recovery.

TNF-α-inhibitors are known to induce skin adverseeffects including psoriasis and alopecia areata. Here, wedescribe a unique pattern of hair loss that has psoriaticand alopecia areata-like features. Diagnosis requiresclinical-pathologic correlation and is supportedby increased catagen/telogen hairs, psoriasiformepidermal hyperplasia, perifollicular lymphocyticinfiltrate, and the presence of eosinophils and plasmacells. Although there are no treatment consensusguidelines, management options include stoppingtherapy, switching to a different TNF-α inhibitor orustekinumab (in severe cases), or continuing TNF-αinhibitor therapy with addition of topical, intralesional,or systemic immunosuppressants.

It is known that eosinophilic fasciitis can be associated with monoclonal gammopathy. There is clinical similarity between eosinophilic fasciitis and morphea profunda, but it is unclear whether morphea profunda might be associated with monoclonal gammopathy. The temporal quantification of gammopathy in morphea profunda has not been well characterized. We describe four patients with morphea profunda that were associated with monoclonal gammopathy. Three were associated with monoclonal IgG protein and one with IgM. No patients in our series developed myeloma. In conclusion, the association of monoclonal gammopathy is not unique to eosinophilic fasciitis and scleromyxedema. Further studies are necessary to characterize further the relationship between the two conditions.

Importance

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare malignant neoplasm with cutaneous manifestations and a rapidly progressive clinical course. The diagnosis relies on characteristic clinicopathologic and immunopathologic features. However, the overlap of immunophenotypic features with other cancers, as well as newly discovered interpersonal and intrapersonal phenotypic variations, renders the identification of BPDCN challenging. A greater understanding of the proteins expressed by BPDCN might facilitate its recognition and provide insights into its clinical behavior.

Observations

In 7 of 9 patients at 4 tertiary care institutions, immunohistochemical analysis demonstrated strong CD31/PECAM-1 (platelet endothelial cell adhesion molecule 1) expression by neoplastic cells. Combined with similar findings observed in 1 former patient, 8 of 10 cases of BPDCN were CD31/PECAM-1 positive.

Conclusions and relevance

Expression of CD31/PECAM-1 by BPDCN adds new information about the antigenic profile of this unusual neoplasm. CD31/PECAM-1 influences multiple cell functions including adhesion, apoptosis, coagulation, host response, and protein synthesis that might affect clinical features of BPDCN such as hemorrhage, aggressive tumor growth, and resistance to therapy. Therefore, the potential role of this molecule in the tumor formation and progression of BPDCN warrants additional exploration.