Rare type of calvarial defects seen in patients with neurofibromatosis type-1 (NF1) is presented. The issues of pathogenesis and management are discussed. Two cases of NF1 with skull defects in the region of the lambdoid suture are reported. The possible etiological basis and nature of these type of defects and management issues are discussed. The calvarial skull defects in the lambdoid suture region are rare defects in NF1 patients. The possible reason of the progressive nature of these type of lesions can be the cerebrospinal fluid pulsations behaving like "growing skull fractures," especially when not associated with structural lesions. It leads to progressive enlargement of the small congenital defects in the region of the lambdoid suture and abnormal susceptibility of bones for resorption. For these defects, conservative management is suggested due to its progressive nature and high chances of operative treatment failure.