RESUMO
Lymphoblastic lymphoma is a group of non-Hodgkin lymphomas that account for approximately 2% of all lymphomas. This is a report of a case of a young girl presenting with a solitary scalp mass which was resected. Histopathological examination of the mass along with bone marrow analysis revealed primary cutaneous B-cell lymphoblastic lymphoma. A nine-year-old girl presenting with an asymptomatic erythematous, non-tender scalp mass present for 12 months was admitted. Skull and brain were intact and devoid of any pathological findings on computed tomography imaging. Systemic examination also showed no evidence of mass lesion in other parts of the body. The lesion was resected and referred for pathological analysis. Microscopic study revealed heavy diffuse dermal and subcutaneous infiltration of monomorphous medium-sized mononuclear cells, with fine chromatin, scant cytoplasm, and variable nucleoli along with intact epidermis and presence of grenz zone. Tumor cells dissect through the collagen fibers. Extensive mitotic figures and focal infiltration of the skin adnexa are seen. IHC study revealed that TdT, CD79a, CD99, CD45, CD20, and Ki67 markers were positive. According to these findings, a definitive diagnosis of primary cutaneous lymphoblastic lymphoma of B cell type was concluded. The 1-year follow up after necessary treatment revealed normal findings without traces of recurrence. Lymphoblastic lymphomas (LBL) are a neoplasm of immature B cells belonging to the B-(B-LBL) or T-cell lineage (T-LBL) that accounts for approximately 2% of all lymphomas. Lymphoblastic lymphoma (LBL) is similar to acute lymphoblastic leukemia (ALL) and the differentiation between these neoplasms is based upon proportion of involvement of lymphoblasts in bone marrow. It has a higher male to female predominance, higher incidence in older children and younger adults, and a relatively higher frequency of CNS and gonadal involvement. The differential diagnosis is based on immunohistochemistry study of B-cell linage tumor markers. Cutaneous involvement is present in about one third of patients with B-LBL but rarely in patients with ALL.