The calvaria of a young adult male from the early medieval burial complex Zvonimirovo (northern Croatia) exhibited the presence of a remodelled solitary lesion embracing the course of the sagittal suture line near the bregma. The small concave antero-posteriorly (AP) elongated – ovoid defect in the midline of the calvarial vault, with marginal cortical bone deposition, was indicative of a once soft-tissue lesion (cystic) development. There were no indicators – neither traumatic nor pathological, which would suggest a different type of lesion or variation. Beside the macroscopic approach, we aimed to use computed tomography (CT) support in interpreting the present non-traumatic dry bone lesion. The CT scans generated well-demarcated irregular and AP elongated lythic lesion (erosion) of the outer table, with osteosclerotic borders, ending up in the diploë, i.e. lacking the involvement of the inner calvarial vault surface (inner table). In this study, the differential diagnosis involved dermal versus epidermal inclusion cyst, sinus pericranii variant in association with the calvarial defect and inflamed atheroma evaluation. The most probable diagnosis of the present, apparently, skin-based dry bone lesion was a variant of a superficial congenital dermal inclusion cyst which was located in the (onetime) scalp. This was suggested by its gross morphology, midline localization, the appearance in early age and the tendency of minor invasiveness when compared to epidermoid. The once soft-tissue feature occurrence in the scalp instead of deeper in the calvaria was suggested by the erosion of the external calvarial vault (ending up slightly in the diploë), i.e. the absence of the inner calvarial vault surface involvement. The accompanying cortical bone deposition surrounding dry bone lythic lesion was suggestive of the past marginal inflammation associated with once soft-tissue feature. The possible presence of a sinus pericranii variant was excluded by the generated CT scans, while atheroma was ruled out due to the lesion localization and the age of the individual.