Extramedullary hematopoiesis in a pyogenic granuloma: a case report and review.
BACKGROUND
Extramedullary hematopoiesis in the adult life is usually associated with hematological disorders. It can often occur in several organs under certain pathological conditions, including the spleen, liver, and skin, which are normal sites during the embryogenesis, the skin being very uncommon.


METHODS
A case of extramedullary hematopoiesis in a granuloma pyogenicum at the anterior aspect of the right thigh of a 31-year-old Japanese man is reported.


RESULTS
Histologic examination revealed an ulcerated polypoid lesion composed of numerous newly formed capillaries and a myxoid edematous stroma. In addition, three islands of hematopoietic precursors were found.


CONCLUSIONS
This is, to our knowledge, the second case of extramedullary hematopoiesis in a granuloma pyogenicum. We believe that vascular lesions have potential to generate hematopoietic precursor cells; however, hematopoiesis will only occur in a setting of adequate microenvironment, as it occurs in the bone marrow.
Department of Pathology, Tokyo Medical University, Nishi-Shinjuku, Shinjuku-Ku, Tokyo 160-8402, Japan.
Suzana M
SM
Vega Harring
Madinyet
M
Niyaz
Shinya
S
Okada
Motoshige
M
Kudo
D000328:Adult; D017789:Granuloma, Pyogenic / Q000150:complications / Q000473:pathology*; D006411:Hematopoiesis, Extramedullary; D006801:Humans; D008297:Male; D012871:Skin Diseases / Q000150:complications / Q000473:pathology*; D013848:Thigh