Blastic Plasmacytoid Dendritic Cell Neoplasm: A Case Series and Review.

ABSTRACT: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy that frequently has cutaneous manifestations. The diagnosis can be a challenge because of its heterogenous clinical presentation, ranging from a brown or violaceous solitary nodule or patch to mixed, disseminated lesions. Furthermore, BPDCN tumor cells express immunohistochemical markers in common with acute myeloid leukemia, which can lead to misdiagnosis. Timely diagnosis requires awareness of its cutaneous manifestations and unique histopathology and immunophenotype. We present a case series of patients diagnosed with BPDCN and review the cutaneous and histopathologic characteristics of this uncommon entity.

What lies beneath: Cutaneous involvement of mantle cell lymphoma underlying an insect-bite-like reaction.

Mantle cell lymphoma (MCL) is an uncommon subtype of mature B-cell non-Hodgkin lymphoma characterized by specific morphologic, immunophenotypic, and genetic characteristics, namely the t(11;14)(q13;q32) chromosomal translocation with resultant cyclin D1 overexpression. MCL has a generally aggressive course and is often widely disseminated at the time of diagnosis. Skin involvement is exceedingly rare and is seldom the first manifestation of MCL. We present a case of MCL in an 84-year-old man with cutaneous involvement as the first manifestation, discovered incidentally after biopsy of a persistent nodule believed to be an insect bite. This case not only serves to raise awareness of the possibility of MCL presenting in the skin but also to point out that MCL can have lesions with both an insect-bite-like reaction and a deeper dermal MCL infiltrate.

An unusual case of cutaneous Waldenström macroglobulinemia with the MYD88 L265P mutation.

Waldenström macroglobulinemia is a lymphoplasmacytic lymphoma with bone marrow involvement and a monoclonal IgM gammopathy. Infiltration of the skin by neoplastic cells is very rare, and it can be difficult to distinguish from marginal zone lymphoma. The MYD88 L265P mutation is strongly associated with Waldenström macroglobulinemia, and it may be helpful in differentiating the two disorders, although the presence of this mutation is not specific, and other factors must be considered when making the final diagnosis. We present a diagnostically challenging case of cutaneous Waldenström macroglobulinemia in which the MYD88 L265P mutation was identified in the skin but not in the bone marrow, due to a low tumor burden.

Multiple flat-topped scaly violaceous papules.

Epidermodysplasia verruciformis (EV) is an autosomal recessive genodermatosis characterized by susceptibility to beta-genus human papillomavirus (HPV) infection. Owing to TMC6/EVER1 and TMC8/EVER2 mutations that lead to abnormal transmembrane channels in the endoplasmic reticulum involved in immunological pathways, keratinocytes cannot combat infection from non-pathogenic HPV strains. Mutations involving RHOH, MST-1, CORO1A, and IL-7 have also been associated with EV in patients without TMC6 or TMC8 mutations. We highlight a 27-year-old man with multiple violaceous flat-topped papules with scale and irregular borders distributed on his chest, extremities, abdomen, and back. The striking physical examination and the subsequent biopsy findings of enlarged nests of cells in the granular and spinous layers with blue-gray cytoplasm and keratohyaline granules confirmed the diagnosis. We conclude with a brief discussion on the differential diagnosis, which includes confluent and reticulated papillomatosis, Darier disease, and disseminated superficial actinic porokeratosis.

Successful treatment of facial papules with electrodessication in a patient with Birt-Hogg-Dubé syndrome.

We report a case of a 51-year-old Hispanic female who presented with a several year history of multiple flesh colored papules of cosmetic concern on the nose and medial cheeks. Biopsies revealed fibrofolliculoma and trichodiscoma. The patient was referred for genetic testing and was found to be positive for the FLCN gene defect, confirming a diagnosis of Birt-Hogg-Dubé syndrome. Further work-up with screening renal ultrasound and CT scan of the thorax and abdomen was unrevealing. For treatment of these skin lesions, dermasanding was attempted initially with only minimal benefit. She subsequently had multiple lesions treated with electrodessication at a low setting and was very pleased with the results. Curettage was not performed and importantly, there has yet to be a recurrence of lesions treated with only hyfrecation.

Imiquimod 5% cream as adjunctive therapy for primary, solitary, nodular nasal basal cell carcinomas before Mohs micrographic surgery: a randomized, double blind, vehicle-controlled study.

BACKGROUND: Imiquimod 5% cream is currently approved for treatment of nonfacial, superficial basal cell carcinomas (BCCs). Topical imiquimod might be a reasonable candidate for adjunctive therapy of nodular, nasal BCCs before Mohs surgery. OBJECTIVE: To observe the effectiveness of imiquimod 5% cream in reducing the number of Mohs stages, defect size, cost of Mohs surgery, and reconstruction. METHODS: Patients applied the study medication nightly for 6 weeks with occlusion followed by a 4-week rest period before Mohs surgery was performed. RESULTS: No differences were demonstrated in the number of Mohs stages, defect sizes, or costs between the two groups, possibly because of our small sample size. Only five of 12 patients (42%) in the treatment group were found histologically clear of tumor (complete responders). CONCLUSION: Imiquimod 5% cream was not helpful as an adjunctive treatment of nodular, nasal BCCs before Mohs surgery, but a larger study might show a benefit. Clearance of nodular, nasal BCCs treated with imiquimod prior to Mohs surgery was less than described in previous studies. Nasal BCCs may be more resistant to imiquimod treatment. Local inflammatory reactions limit imiquimod's usefulness in this setting. Histologic assessment of nasal BCCs treated with imiquimod is recommended.