Case presentation
A 9-years-old girl with the chief complaint of a solitary mass present
on her scalp for almost 12 months with no significant past medical
history was admitted to hospital. An erythematous lesion with the size
of 4.5cm was noted on physical examination. No pruritus or tenderness of
lesion was evident. The patient did not complain of fever or weight loss
during recent months. Computed tomography scan (CT-scan) of the brain
revealed no involvement of skull or brain tissue. Systemic examination
further revealed no evidence of mass lesion in other parts of the body.
Laboratory evaluations revealed normal findings. Hence, en blocresection was achieved and the lesion referred to laboratory for further
pathological study. Microscopic analysis revealed heavy diffuse dermal
and subcutaneous infiltration of monomorphous medium-sized mononuclear
cells, with fine chromatin, scant cytoplasm, and small nucleoli. Mitotic
figures were frequent and tumor cells were observed infiltrating between
collagen bundles. The integrity of epidermis remained intact (Figures 1,
2). Based on immunohistochemistry (IHC)analysis, CD99, TdT, and CD79a
markers were strongly positive in tumor cells with diffuse pattern.
Furthermore, CD45 and CD20 markers were also positive in some of the
tumor cells (Figures 3,4). Ki67 marker was positive in approximately
40% of tumor cells (Figure 5). Tumor cells were negative for MNF116,
EMA, CK7, CK20, Melan A, HMB45, TTF1, S100, Chromogranin, NSE, CD3,
CD56, and desmin. Bone marrow biopsy revealed that the tumor had not
involved the marrow and full-body CT-scan and whole body bone scan was
devoid of any pathological findings. Therefore, the definitive diagnosis
of primary cutaneous lymphoblastic lymphoma of B cell type was
concluded. One-year follow-up of the patient after proper treatment
revealed normal findings and no trace of recurrence.