652 Actinomycosis. 



tractions which occasionally cause marked deformity of the 

 organ, especially an abnormal upward curvature and a contrac - 

 lion of the whole organ (Axe). 



In the maxillary bones the disease usually begins in the 

 marrow cavity or periosteum. In the iirst instance the spongy 

 bone substance is replaced by a soft sarcoma-like tissue re- 

 sulting in breaking down of the bony trabeculae and distension 

 of the lamellae. The aifected bone appears much enlarged 

 with the external lamella considerably thickened as a result 

 of osteoplastic inflannnation (periostitis ossificans), eventually 

 becoming perforated. This is followed by the projection of 

 soft cauliflower-like proliferations under the skin, into the 

 mouth or into the pharynx. 



In the interior of the tumor the bony substance has been 

 reduced to an open network composed of thin trabeculae, as 

 may be recognized upon section by its white color and hard 

 consistency. The soft tissue proliferation surround also the 

 roots of the teeth and may cause them to be forced out of 

 their alveoli. Thus teeth with healthy crowns may be found 

 to have their roots imbedded in the soft su])stance of a tumor. 



The granulations which project from the gums consist of 

 hemispherical, irregular masses varying in size from a pea 

 to that of a walnut. Sometimes they perforate the gums or 

 mucous membranes and project into the mouth cavity. Fre- 

 quently they present an ulcerous surface. 



After maceration the atfeeted maxillary bone appears to consist of a more 

 or less perforated external bony lamella and an internal open spongy structure. 

 This condition recalls vividly to mind the deformity formerly designated as "spina 

 ventosa ' ' resulting from myelosarcomatous invasion. It is significant that 

 aetinomycomata usually develop near the molar teeth and are only exceptionally 

 met with on the toothless portion of the gums or in the region of the incisors 

 (Moussu). 



Tumors originating in the periosteum of the maxillary 

 bone are usually much firmer and tougher in consistency while 

 upon section they are found to contain fewer and smaller 

 centers of softening. They occur on the external or internal 

 face of the maxilla, occasionally also near the incisors and 

 are attached only loosely to the skin or mucous membrane, 

 but are firmly united with the periosteum. In exceptional 

 cases they may give rise to the development of so called 

 "dermal" horns with bony bases (Johne). 



Tumors of the superior maxillary bone are apt to spread 

 to the subparotideal region and to the fossa pterygo-palatina. 

 In exceptional cases they force themselves through the natural 

 foramina, perforate the flat basal bones of tlie cranium, and 

 enter the cranial cavity, affecting the meninges and even the 

 brain itself. On the other hand they may extend from the 

 alveolar process to the antrum of Highmore. The disease may 

 also develop primarily in the latter (Bang). In such cases 

 after filling out the antrum and breaking down the bony tissue. 



