Indeterminate Cell Histiocytosis: A Case Report

Indeterminate Dendritic Cell Tumor: A Report of Two New Cases Lacking the ETV3-NCOA2 Translocation and a Literature Review

Indeterminate dendritic cell tumor (IDCT) is a cutaneous proliferation of histiocytes that share morphologic and immunophenotypic properties with Langerhans cells. IDCT was recently included in the updated WHO classification of tumors of hematopoietic and lymphoid tissues. Recent studies have shown that some cases of IDCT demonstrate an ETV3-NCOA2 translocation, supporting the idea that IDCT is a clonal neoplasm. We report 2 new cases of IDCT at our institution lacking the ETV3-NCOA2 translocation. We also present a comprehensive review of reported cases of IDCT in the medical literature. Eighty-five cases of IDCT were reported in the literature between 1985 and 2016. The median age at diagnosis was 45 years. In contrast to Langerhans cell histiocytosis, IDCT is limited to the skin in the majority of cases (88%) and generally follows an indolent clinical course. Most reported lesions are cured with complete excision. However, the histologic features of IDCT and langerhans cell histiocytosis are similar. Conjoint immunostaining for CD1a and langerin is necessary for optimal classification.

Indeterminate cell histiocytosis in a Chinese patient with progressive and extensive nodular lesions and mixed indeterminate cell and macrophage-monocyte lineage

Indeterminate cell histiocytosis (ICH) is an extremely rare cutaneous neoplastic disorder. It has the immunophenotypic features of both Langerhans and non-Langerhans cell histiocytosis. We report here a case of a healthy young Chinese woman who presented with disfiguring, thick, infiltrated cutaneous nodules on the face, trunk and extremities which appeared progressively over a period of 4 years. No systemic involvement has been detected so far. Results of a skin biopsy showed diffuse dermal infiltration of histiocytoid cells with indented nuclei and positive staining for S100 and CD1a and negativity for CD207 (langerin). Admixed within were some CD68-positive foamy histiocytes and multinucleated giant cells with focal expression of CD163. Although the clinical presentation is more typical of progressive nodular histiocytosis, the histology and immunoprofile is consistent with ICH. Our report adds to the limited case reports in the current literature of ICH in the Chinese population.

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.

Generalized Indeterminate Cell Histiocytosis Presenting as Eroded Papules and Crusts

Indeterminate cell histiocytosis (ICH) is a very rare histiocytic disease. We reported a case of generalized ICH presenting as eroded papules and crusts, accompanied with intermittent fever, pulmonary disorder, lymphadenectasis in the mediastinum, and the retroperitoneum. The histopathology indicated a neoplasm that was composed of small nests of large cells with ample pale cytoplasm. Immunohistochemistry results and the absence of Birbeck granules led us to the diagnosis of ICH. Four months later, the patient died of anemia, ascites, and swelling of the limbs.

Indeterminate cell histiocytosis with naïve cells

Histiocytoses are a heterogeneous group of disorders characterized by proliferation and accumulation of cells of mononuclear-macrophage system and dendritic cells. Histiocytoses are categorized according to the cell of origin into Langerhans cell histiocytosis (LCH), Non Langerhans cell histiocytoses and indeterminate cell histiocytosis (ICH). ICH is an extraordinary rare neoplastic dendritic cell disorder that has poorly understood histogenesis and pathogenesis. It is characterized by a proliferation of dendritic cells, which mimic Langerhans cells immunophenotypically (positive for CD1a and S-100 protein), but lack Birbeck granules characteristic of Langerhans cells. Twenty-four year-old Egyptian male was presented with reddish brown chest wall nodule. Clinical, histopathological, immunohistochemical and ultrastructure features are typical for ICH. He was in a good state without any evidence of recurrence or metastasis after 24 months follow up. Peculiar histopathological features were detected in the present case. Many unidentified cells with Hematoxylin & Eosin Langerhans like features showed negative staining for S-100, CD1a, Langerin and CD68. In absence of cellular atypia and mitosis, the infiltrating cells showed epidermotropism that was reported once in ICH as well as neural and perineural invasion that were not previously reported. Therefore we prefer using a tentatively designated diagnosis; dendritic cell tumor, not otherwise specified or newly proposed diagnosis (Indeterminate cell histocytosis with naïve cells) for the present case.

S100-negative indeterminate cell histiocytosis in an African American child responsive to narrowband ultraviolet B

Indeterminate cell histiocytosis is a rare cutaneous disease characterized by the presence of dendritic cells that lack Birbeck granules and immunophenotypically shares features of both Langerhans cells and macrophages. We describe a case of a 4-year-old African American boy affected by a disseminated, exclusively mucocutaneous form of indeterminate cell histiocytosis. The eruption was successfully treated with narrowband ultraviolet B. The peculiar negativity of the Langerhans cell marker S100 is also discussed.

Indeterminate cell histiocytosis: fact or fiction?

Indeterminate cell histiocytosis is a rare disorder, in which the predominant cells have the characteristics of both Langerhans cells and macrophages. We, in this study, describe 18 patients and compare them with those previously published. Most patients were adults with either solitary or multiple red-brown papules or nodules. While most lesions were confined to the skin, both conjunctival and bony involvement was seen. Histologically, the lesions showed patterns resembling those described for xanthogranulomas, with predominantly oncocytic (nine patients), spindled (five patients), scalloped (two patients) or vacuolated (two patients) macrophages. The accompanying infiltrate was mainly lymphocytic, although eosinophils and occasionally plasma cells were seen. All lesions were positive for macrophage markers, such as KP1 (CD68) and Ki-M1p, as well as for S-100 protein and showed variable reactivity for CD1a. No Birbeck granules were seen ultrastructurally in one patient. Some patients shared features with sinus histiocytosis with massive lymphadenopathy. It is unclear whether this disorder is a separate entity or represents various macrophage disorders identified at various time points in the inflammatory response. Ratzinger G, Burgdorf WHC, Metze D, Zelger BG, Zelger B. Indeterminate cell histiocytosis: fact or fiction? A clinicopathological series of 18 patients.