Dyke–Davidoff–Masson syndrome or fibrous dysplasia: response to a “Letter to the Editor”

Abstract

Dear Sir, We thank Dr. Donmez for his comments. When dealing with archaeological human remains, one faces the challenge of diagnosing diseases without the patient’s clinical history or routine laboratory tests, and must rely on clues from the skeleton regarding the condition of the soft tissues. The situation is further complicated as many diseases may be manifested in a similar manner in the skeleton, while in many others, osseous changes do not necessarily occur. Sampling of the skeletal remains, for histological, genetic or isotope analyses, is a destructive process, which cannot always be carried out on fragile specimens. Thus, the use of imaging is a valuable tool in paleopathology. Radiologists, however, must take into consideration that taphonomic processes (i.e. postmortem and post-depositional effects, such as soil composition or animal scavenging) may significantly alter the morphology of the dry bones, thus affecting the accuracy of the imaging-based diagnosis [1]. Specifically, the slightly blurred appearance in the ancient skull, which was perceived by the author of the comment on our paper as “ground-glass appearance”, is actually a common feature in imaging of archaeological specimens (Fig. 1). It is due to taphonomic changes, rather than to a pathological process. Fibrous dysplasia (FD), which was suggested in the differential diagnosis in our original letter [2], is thought to be caused by a malformation during the bone’s development, resulting in the formation of islands of fibrous tissue within the bone marrow, gradually replacing it and the adjacent cortical bone [3]. Symptoms include swelling of the affected area, asymmetry of the cranial bones, ophthalmological defects, hypertrophy of the temporal bone or of the skull base, pathological fractures and skin depigmentation [4]. FD can appear in a monostotic (in a single bone or single focus of involvement) or polyostotic (in several bones or foci) forms: 50–100 % of the latter involve the cranium, whereas only 10–20 % of the former are manifested in the skull [5, 6]. FD is more common in the ribs, femur, jaw and tibia in its monostotic form, and in the lower limbs, upper limbs and pelvis in its polyostotic form [3]. In our case, only one area of the skull is affected, and no lesions associated with FD were detected in the rest of the skeleton. Although in the cranium, the most commonly affected bone is the frontal one [4], as in this case, the “ground glass appearance” typical of FD, which reflects the admixture of fibrous and osseous tissue in the lesion [5], is more common in the facial bones and the skull base, than in the cranial vault [7]. Furthermore, postmortem degeneration of the fibrous tissue within the lesion would most likely result either in an empty cyst-like lesion or in an area containing irregular bone trabeculae [6]. In our case, the diploe is expanded, but its internal structure does not appear disturbed (Fig. 1a). Most importantly, FD of the skull typically causes the outer table of the diploe to expand, while the inner table remains normal [4], contrary to the case at hand. Outwards expansion of the outer diploic table is unlikely to involve changes in the cranial content [4]. In our case, however, the invagination of the frontal bone and the elevation of the petrous ridge (Fig. 2) suggest that This article is a response to a "Letter to the Editor" (http://dx.doi.org/ 10.1007/s00234-012-1060-6). V. Slon : I. Hershkovitz (*) Department of Anatomy and Anthropology, Sackler Faculty of Medicine, Tel-Aviv University, Ramat-Aviv, Israel e-mail: anatom2@post.tau.ac.il