S100/CD1a positive dermal infiltrate as an initial presentation of chronic myelomonocytic leukaemia

A Case of Indeterminate Cutaneous Dendritic Cell Tumors in the Setting of Chronic Myelomonocytic Leukemia

ABSTRACT

Chronic myelomonocytic leukemia (CMML) is a rare hematopoietic stem cell neoplasm. Indeterminate dendritic cell neoplasm (IDCN) is an extraordinarily rare histiocytosis that may manifest secondarily to CMML. A 75-year-old man with a 2-year history of CMML presented for multiple cutaneous lesions on his head and neck. Biopsy results yielded a dense diffuse infiltrate of large pleomorphic cells, which were positive for CD1a, S100, and CD56 with weak positivity for CD43 and CD68. Given his history of CMML, the patient was diagnosed with IDCN. This may indicate a progression of his CMML or transformation to acute leukemia; therefore, a systemic workup was recommended. IDCN may manifest secondary to a wide number of hematopoietic malignancies, with CMML being a rare occurrence. Recorded responses to phototherapy are reassuring, whereas systemic therapy may be appropriate for widespread cases. Remaining vigilant for cutaneous changes in patients with CMML will help prevent misdiagnosis and encourage prompt initiation of appropriate treatment.

Blastic Indeterminate Dendritic Cell Tumor Associated With Chronic Myelomonocytic Leukemia

ABSTRACT

Indeterminate dendritic cell tumor (IDCT) is an exceedingly rare neoplasm that can be associated with hematopoietic malignancies. We report a case of multifocal cutaneous blastic indeterminate dendritic cell tumor (BIDCT) in a 75-year-old man with chronic myelomonocytic leukemia showing blastic histiocytoid morphology, positivity for CD1a and S100, and no expression of langerin. We present a literature review on the 11 reported cases of IDCTs/BIDCTs associated with chronic myelomonocytic leukemia (CMML), including this case. The clinicopathological characteristics have been summarized. The IDCT and CMML cells are clonally related in 4 tested cases. Patients with IDCT/BIDCT associated with CMML seem to have worse clinical outcomes compared with patients with IDCT not associated with CMML.

Indeterminate dendritic cell neoplasm of the skin: A 2-case report and review of the literature

Indeterminate dendritic cell neoplasm (IDCN) is an exceedingly rare and mostly cutaneous histiocytosis, frequently associated with other hematopoietic malignancies. We report 2 cases of multilesional cutaneous IDCN. A 55-year-old male with no associated malignancy and complete response to ultraviolet phototherapy; and a 72-year-old male with chronic myelomonocytic leukemia (CMML). Both cases showed histiocytoid cytology, positivity for CD1a and no expression of langerin or BRAF^V600E . With our patients, the literature describes 79 cases of IDCNs, including 65 (82%) with only skin involvement, 7 cases (9%) with involvement of skin and a second site, 5 cases (6%) involving lymph nodes only, 1 splenic lesion and 1 systemic disease. Seventeen cases (22%) were associated with other hematopoietic malignancies, most commonly CMML (6 cases), follicular lymphoma (4 cases) and acute myeloid leukemia (3 cases). All IDCNs associated with myeloid malignancies were limited to the skin, while most cases associated with lymphoma were limited to lymph nodes. Reported responses of cutaneous lesions to ultraviolet phototherapy are encouraging, while systemic chemotherapy is appropriate for clinically aggressive cases and treatment of associated malignancies. Recognition of the clinico-morphologic spectrum of IDCNs should prevent misdiagnoses and prompt investigation of possible associated neoplasms.