Cutaneous extramedullary hematopoiesis with a preponderance of atypical megakaryocytes in myelofibrosis

Unique molecular and functional features of extramedullary hematopoietic stem and progenitor cell reservoirs in humans

Rare hematopoietic stem and progenitor cell (HSPC) pools outside the bone marrow (BM) contribute to blood production in stress and disease but remain ill-defined. Although nonmobilized peripheral blood (PB) is routinely sampled for clinical management, the diagnosis and monitoring potential of PB HSPCs remain untapped, as no healthy PB HSPC baseline has been reported. Here we comprehensively delineate human extramedullary HSPC compartments comparing spleen, PB, and mobilized PB to BM using single-cell RNA-sequencing and/or functional assays. We uncovered HSPC features shared by extramedullary tissues and others unique to PB. First, in contrast to actively dividing BM HSPCs, we found no evidence of substantial ongoing hematopoiesis in extramedullary tissues at steady state but report increased splenic HSPC proliferative output during stress erythropoiesis. Second, extramedullary hematopoietic stem cells/multipotent progenitors (HSCs/MPPs) from spleen, PB, and mobilized PB share a common transcriptional signature and increased abundance of lineage-primed subsets compared with BM. Third, healthy PB HSPCs display a unique bias toward erythroid-megakaryocytic differentiation. At the HSC/MPP level, this is functionally imparted by a subset of phenotypic CD71+ HSCs/MPPs, exclusively producing erythrocytes and megakaryocytes, highly abundant in PB but rare in other adult tissues. Finally, the unique erythroid-megakaryocytic-skewing of PB is perturbed with age in essential thrombocythemia and β-thalassemia. Collectively, we identify extramedullary lineage-primed HSPC reservoirs that are nonproliferative in situ and report involvement of splenic HSPCs during demand-adapted hematopoiesis. Our data also establish aberrant composition and function of circulating HSPCs as potential clinical indicators of BM dysfunction.

A Case of Primary Myelofibrosis With Transformation to Leukemia Cutis

ABSTRACT

We report an extraordinary case of primary myelofibrosis with transformation to leukemia cutis. A 64-year-old Caucasian man with a history of JAK2-positive primary myelofibrosis presented with erythematous papulonodules on his right lower extremity. A punch biopsy revealed a normal epidermis with an underlying diffuse dermal infiltrate composed of medium-to-large-sized myeloid cells and leukocytes. Neoplastic cells were immunoreactive for LCA, CD34, CD61, CD117, and CD68 and negative for lysozyme, CD20, CD3, myeloperoxidase, and TdT. These findings were consistent with a diagnosis of leukemia cutis. A concurrent bone marrow biopsy demonstrated a markedly fibrotic, hypercellular marrow without a significant increase in blasts. With no morphologic evidence of bone marrow involvement by acute myeloid leukemia, our case suggests that the patient's primary myelofibrosis transformed to leukemia cutis. Our patient died 2 months after the onset of his skin nodules. Our case demonstrates that leukemia cutis should be included in the differential diagnosis for cutaneous nodular lesions in patients with a history of an advanced-stage hematological malignancy.

Fine-needle aspiration diagnosis of clonal extramedullary hematopoiesis in a case of myeloproliferative neoplasm

Extramedullary hematopoiesis (EMH)-the proliferation of hematopoietic progenitors outside of the bone marrow (BM) is a well-known phenomenon in myeloproliferative neoplasms (MPN). Abundant literature describes EMH at various body sites in cases of MPN, and some studies showed the presence of cytogenetic changes associated with MPN in the EMH tissues. We present a case of an 80-year-old female, with a history of MPN, presenting with mediastinal adenopathy. The transbronchial fine-needle aspiration (FNA) of the mediastinal lymph node showed EMH with atypical megakaryocytes and del(13q) demonstrated by fluorescence in situ hybridization. The subsequent BM biopsy demonstrated myelofibrosis with atypical megakaryocytes harboring the same cytogenetic abnormality. Our case highlights the capability of FNA cytology for providing accurate morphologic, immunohistochemical, and cytogenetic diagnosis of clonal EMH.

A Rare Presentation of Extramedullary Hematopoiesis in Post-polycythemic Myelofibrosis

Polycythemia vera is a clonal proliferative disorder of the bone marrow that could possibly evolve into myelofibrosis in its natural course. Progression to myelofibrosis is usually a late stage complication and presents clinically with refractory cytopenias and extramedullary hematopoiesis (EMH). EMH can occur in any tissue during the course of post-polycythemic myelofibrosis. However, skin and cardiac involvements seems to be very rare. We present a 56-year-old woman with post-polycythemic myelofibrosis refractory to treatment, developing EMH after splenectomy in various organs, exceptionally the skin and the heart. Along with the case, the clinical presentations, treatment options, prognostic significance of EMH and the role of cytogenetics is discussed in the light of the literature.

Cutaneous extramedullary hematopoiesis in a patient with idiopathic myelofibrosis

Idiopathic myelofibrosis (IM) is a chronic myeloproliferative disorder and some cases of IM have extramedullary hematopoiesis. Extramedullary hematopoiesis is commonly seen in the liver, spleen and lymph nodes, but cutaneous extramedullary hematopoiesis (CEH) is very rare in cases of IM. We report a case of CEH in a 65-year-old Japanese woman with IM. This patient had many hard brownish nodules on her chest, abdomen and scalp. Histopathological examination of the nodule on her chest showed the existence of various stages of immature erythrocytes, leukocytes and megakaryocytes indicating that these hard nodules showed extramedullary hematopoiesis in the dermis. The proliferation of these immature cells in the dermis plays an important role in the pathogenesis of CEH. CEH is a very rare manifestation of IM and progresses slowly.

Cutaneous myelofibrosis

Cutaneous extramedullary hematopoiesis is rare, usually occurring in neonates following intrauterine viral infections, hereditary spherocytosis, or the twin transfusion syndrome. Only 20 cases of cutaneous extramedullary hematopoiesis have been reported in adults, all with myelofibrosis. The cutaneous infiltrates may be atypical and difficult to distinguish from leukemia cutis. We have studied a 65-year-old woman with myelofibrosis and approximately 40 violaceous, firm, non-tender cutaneous nodules measuring 1 to 4 cm in diameter, located on her abdomen near a splenectomy scar. Histologically, the lesions had a dense infiltrate of myeloid cells in all stages of maturation, atypical large cells with multilobate nuclei or multiple nuclei, resembling atypical megakaryocytes, and fibroblasts. Although the patient received erythropoietin therapy prior to the development of the nodules, erythroid progenitors were not seen. Reticulin was increased particularly surrounding the atypical megakaryocytes. The myeloid cells stained for chloroacetate esterase and with the polyclonal antibody MAC 387. Atypical megakaryocytes stained for Factor XIIIa and Factor VIII-related antigen. Dendritic Factor XIIIa positive cells were also increased. The skin lesions remain unchanged grossly one year after their development.

Extramedullary hematopoiesis in an adult

Cutaneous extramedullary hematopoiesis is a rare disease, affecting mainly children with intrauterine viral or hematologic disorders. To our knowledge, only about 30 cases have been reported in adults, mainly associated with myelofibrosis. We report a new case of this entity in a 79-year-old woman and comment on the clinical and histologic differential diagnosis.

Cutaneous sclerosing extramedullary hematopoietic tumor in chronic myelogenous leukemia

BACKGROUND

Extramedullary hematopoiesis is a well-documented manifestation of chronic myeloproliferative disorders, most commonly seen in chronic idiopathic myelofibrosis (agnogenic myeloid metaplasia), but rarely in chronic myelogenous leukemia. It typically occurs in the spleen and liver, but has also been described in skin. Microscopically, foci of extramedullary hematopoiesis consist of erythroid and myeloid precursors intermixed with megakaryocytes. The megakaryocytes may elaborate fibrogenic cytokines, which induce proliferation of fibroblasts. The term 'sclerosing extramedullary hematopoietic tumor' has been applied to this latter entity and its resemblance to a fibrohistiocytic neoplasm has been noted.

METHODS

We report the case of a 66-year-old man, whose cutaneous sclerosing extramedullary hematopoietic tumor preceded the diagnosis of chronic myelogenous leukemia.

Subcutaneous extramedullary hematopoiesis in a patient with secondary myelofibrosis following polycythemia vera

We describe the case of a 73-year-old woman with secondary myelofibrosis who developed subcutaneous extramedullary hematopoiesis. Although extramedullary hematopoiesis has been generally observed in primary myelofibrosis, in this case it was seen in myelofibrosis secondary to polycythemia vera. Histological examination of the subcutaneous nodule revealed that the lesion included cells from the myeloid and megakaryocytic series. The skin lesion almost disappeared after treatment with hydroxyurea. We report here this rare manifestation in secondary myelofibrosis including a review of literature.

A case of cutaneous extramedullary hematopoiesis in myelofibrosis with a preponderance of eosinophilic precursor cells

A 48-year-old Korean man with myelofibrosis had erythematous papules and nodules on his scalp, anterior chest, back, lower abdomen, and both thighs. Skin biopsy showed cellular infiltration on the perivascular dermis and subcutaneous fat. Infiltrates were composed mainly of myeloid cells, especially of eosinophilic precursor cells. Erythroid and a few megakaryocytic precursors were also found. We diagnosed cutaneous extramedullary hematopoiesis with an interesting preponderance of eosinophilic precursor cells.

Recombinant human interleukin-3 induces extramedullary hematopoiesis at subcutaneous injection sites in cynomolgus monkeys

Parenteral administration of recombinant hematopoietic growth factors has been sporadically associated with cutaneous complications, including injection site reactions in humans and nonhuman primates. In this study, subcutaneous injection sites were evaluated from 12 cynomolgus monkeys administered a recombinant human interleukin-3 (rhIL-3) at dose levels of 0, 70, or 700 micrograms/kg daily for 18 days. Monkeys administered rhIL-3 developed small (0.5-1-cm-diameter), firm nodules at the subcutaneous injection sites. Histologically, these nodules from 4 of 8 rhIL-3-treated monkeys contained trilineage extramedullary hematopoiesis (EMH) represented by precursors of myeloid, erythroid, and megakaryocytic series cells. The lineage of hematopoietic cells was confirmed by histochemical and immunohistochemical methods. Hematopoietic cells of myeloid and megakaryocytic lineages were more common than erythroid cells. Of myeloid cells, immature eosinophils were more common, which usually formed small sheets or clusters in the panniculus and deep dermis. This report describes, for the first time, the occurrence of cutaneous EMH at the injection sites of recombinant hematopoietic growth factors, which should be differentiated from inflammation. We believe the cutaneous EMH was the exaggerated pharmacologic effect of rhIL-3.

Cutaneous lesions in a case of acute megakaryoblastic leukaemia

We describe the case of a 68-year-old woman who presented with asymptomatic skin nodules and symptoms of anaemia, and was found to have acute megakaryoblastic leukaemia with fibrosis, a condition now believed to correspond to the former diagnosis of acute myelofibrosis. There is only one previous report of skin lesions developing in this condition.

Neutrophilic dermatosis associated with chronic neutrophilic leukemia

Chronic neutrophilic leukemia is an uncommon myeloproliferative disorder. We report a new case that fulfills the clinical and biologic criteria for such a diagnosis. The hematologic disease was revealed by a neutrophilic dermatosis that finally disappeared spontaneously after a duration of 1 year. Despite the lack of parallelism in the course of dermatologic and hematologic manifestations, we believe they were strongly linked. Occurrence of neutrophilic dermatoses in the course of other myeloproliferative disorders is well known. However, in our case, clinical and histologic features could not be used to distinguish between atypical Sweet's syndrome and specific cutaneous lesions because of the mature appearance of both skin and blood neutrophils.