Diagnosis of osteoblastoma by fine-needle aspiration (FNA) is rare, as in most patients, excisional biopsy is performed. We report a case of FNA diagnosis of a spinal osteoblastoma in a lymphangiomatosis patient. The patient had a history of lymphangiomatosis since birth with lymphangiomas removed from various locations, and had radiograph evidence of multifocal vertebral involvement. He presented with an enlarging C3 posterior element vertebral lesion. Clinically and radiologically, it was suspicious for lymphangiomatosis involvement. A computed tomography (CT)-guided FNA yielded a moderately cellular specimen. Lesional cells exhibited plasmacytoid features, fine chromatin, smooth nuclear membranes, and binucleation, in a background of occasional osteoclastic cells, spindle cells, and osteoid matrix. A cytological diagnosis of osteoblastoma was favored and confirmed with follow-up surgical biopsy. We believe that this is the first case reporting an osteoblastoma diagnosed by FNA in a lymphangiomatosis patient. We describe the clinical and cytological findings of osteoblastoma and its differential diagnosis.