https://orcid.org/0000-0003-0077-640X
![A 59-year-old woman with a known history of JAK-2+ (V617F) polycythemia vera (PV) previously managed with venesections was referred for possible progression to post-PV myelofibrosis on the basis of a leucoerythroblastic blood film, raised lactate dehydrogenase (LDH), and newly palpable splenomegaly (palpable at 1 cm below the rib cage). The patient had a significant history of metochondromatosis (a rare autosomal disorder resulting in enchondromas and osteochondroma-like lesions). Bone marrow trephine demonstrated infiltration, with numerous chondromas (panel A; hematoxylin and eosin [H&E] stain; original magnification of bone marrow trephine ×20; black arrow indicates chondromas). Only small areas of hematopoiesis remained and had preserved trilineage hematopoiesis (panel B; H&E stain; original magnification ×40), and reticulin stain demonstrated no increased reticulin deposition or fibrosis (panel C; reticulin stain; magnification ×40). She therefore did not meet the diagnostic criteria for post-PV myelofibrosis, with splenomegaly likely a result of extramedullary hematopoiesis.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/138/22/10.1182_blood.2021013420/5/m_bloodbld2021013420f1.png?Expires=1769241028&Signature=3uujWmyk7y3ybPCcu~UcAS8v33xqzrSrrpbXhwUxjrBWFk7oeqDC7YYwXE8ikkmGy0xX3uenr~kbyMrVYDKfcrd1hnt-hb5hv40nKBm6Mzbe6dn~UW0qODQbQmeQpmkF1GLhXiyb5k37P8N0esX-OBex7S7BqZ3J~I-mbufmKQOGJA0mngI0B8obowtBKlJWNC4UzShrFHT~p2e03AXSswNCO0T-htroE~H~OQhn9JJNVQJVRj3Q6Kfnce0PsDCpSXmKYvsyVyrmSj0PRM1sBsqt6YoUVV3i2jnhdcbDyIRm2xF0eYpISFL0c~uaCS-QHAtQetoWLYcycwzNuopaMA__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
A 59-year-old woman with a known history of JAK-2+ (V617F) polycythemia vera (PV) previously managed with venesections was referred for possible progression to post-PV myelofibrosis on the basis of a leucoerythroblastic blood film, raised lactate dehydrogenase (LDH), and newly palpable splenomegaly (palpable at 1 cm below the rib cage). The patient had a significant history of metochondromatosis (a rare autosomal disorder resulting in enchondromas and osteochondroma-like lesions). Bone marrow trephine demonstrated infiltration, with numerous chondromas (panel A; hematoxylin and eosin [H&E] stain; original magnification of bone marrow trephine ×20; black arrow indicates chondromas). Only small areas of hematopoiesis remained and had preserved trilineage hematopoiesis (panel B; H&E stain; original magnification ×40), and reticulin stain demonstrated no increased reticulin deposition or fibrosis (panel C; reticulin stain; magnification ×40). She therefore did not meet the diagnostic criteria for post-PV myelofibrosis, with splenomegaly likely a result of extramedullary hematopoiesis.
Post-PV myelofibrosis is diagnosed on the basis of both clinical features (eg, anemia or loss of requirement for venesection, splenomegaly, or constitutional symptoms) and pathological/histological findings (eg, grade 2-3 marrow fibrosis or raised LDH). Clinicians should be aware that other conditions can cause a similar picture, including marrow infiltration with both benign (as in our case) and malignant tumors.
A 59-year-old woman with a known history of JAK-2+ (V617F) polycythemia vera (PV) previously managed with venesections was referred for possible progression to post-PV myelofibrosis on the basis of a leucoerythroblastic blood film, raised lactate dehydrogenase (LDH), and newly palpable splenomegaly (palpable at 1 cm below the rib cage). The patient had a significant history of metochondromatosis (a rare autosomal disorder resulting in enchondromas and osteochondroma-like lesions). Bone marrow trephine demonstrated infiltration, with numerous chondromas (panel A; hematoxylin and eosin [H&E] stain; original magnification of bone marrow trephine ×20; black arrow indicates chondromas). Only small areas of hematopoiesis remained and had preserved trilineage hematopoiesis (panel B; H&E stain; original magnification ×40), and reticulin stain demonstrated no increased reticulin deposition or fibrosis (panel C; reticulin stain; magnification ×40). She therefore did not meet the diagnostic criteria for post-PV myelofibrosis, with splenomegaly likely a result of extramedullary hematopoiesis.
Post-PV myelofibrosis is diagnosed on the basis of both clinical features (eg, anemia or loss of requirement for venesection, splenomegaly, or constitutional symptoms) and pathological/histological findings (eg, grade 2-3 marrow fibrosis or raised LDH). Clinicians should be aware that other conditions can cause a similar picture, including marrow infiltration with both benign (as in our case) and malignant tumors.
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![A 59-year-old woman with a known history of JAK-2+ (V617F) polycythemia vera (PV) previously managed with venesections was referred for possible progression to post-PV myelofibrosis on the basis of a leucoerythroblastic blood film, raised lactate dehydrogenase (LDH), and newly palpable splenomegaly (palpable at 1 cm below the rib cage). The patient had a significant history of metochondromatosis (a rare autosomal disorder resulting in enchondromas and osteochondroma-like lesions). Bone marrow trephine demonstrated infiltration, with numerous chondromas (panel A; hematoxylin and eosin [H&E] stain; original magnification of bone marrow trephine ×20; black arrow indicates chondromas). Only small areas of hematopoiesis remained and had preserved trilineage hematopoiesis (panel B; H&E stain; original magnification ×40), and reticulin stain demonstrated no increased reticulin deposition or fibrosis (panel C; reticulin stain; magnification ×40). She therefore did not meet the diagnostic criteria for post-PV myelofibrosis, with splenomegaly likely a result of extramedullary hematopoiesis.](https://ash.silverchair-cdn.com/ash/content_public/journal/blood/138/22/10.1182_blood.2021013420/5/m_bloodbld2021013420f1.png?Expires=1769241029&Signature=EWEFsBEDyXWR-ZvqpSF3NlGfAwegj-azNN3OH1aQ0PQSQReO~tCSxS7O~GETavO~vfOp2yfJ2MZ45L4JyAH7NBTRjY21inKTfyQiVZf87ENQJc4asM3HISPJ3PBKcj8t4u7lCOKf~cVnp5~QxdgxFLdnCA0FCiVXmjaO3vzm2lZYaXX0LdDSj~eunnT7~CuRWfiTkbf1uQadWgdozwXsGz2He00Sznx8N7PP0AbyBNM-98IlR9s-I3t4OdqBt9Xl8U1H5gJ~zE0~uv4yXWHsPR9JuD82DWvdQCweMVhbGRU4AEZVQkhDR0U0clMAayR92Pqb0BqQkZ8HrcJ7O1qVJw__&Key-Pair-Id=APKAIE5G5CRDK6RD3PGA)
