Metaplastic Bone Formation in the Abdominal Wall—An Incidental Finding in a Patient With Gastric Cancer. Case Report and Hypothesis About Its Histogenesis

Abstract

A 64-year-old man was hospitalized showing symptoms suggesting gastric cancer. The gastroscopy showed a 70 × 30-mm tumor. The intraoperatory findings indicated an inoperable gastric tumor located in the antrum and gastric body, which invaded the spleen and pancreas. The abdominal incision was closed without performing gastrectomy. Considering his general condition, after 1 month, he was transferred to our hospital. We decided to perform a total gastrectomy of necessity, spleno-pancreatectomy, and dissection of regional lymph nodes. The surgical incision was performed along to the previous one. At palpation, a well-defined nodule with hard consistency was observed in the surgical scar, which microscopically was composed by osteoblasts-lining mature lamellar bone intermingled with osteoid and cartilage in the intermediary layer and fibroblasts in the central area, without atypia. The final diagnosis was localized metaplastic bone formation. This is a rare condition which can be related to trauma or surgery and should be differentiated by foreign-body granuloma and osteosarcoma.

Successful treatment of a giant ossified benign mesenteric schwannoma

“…Antoni type B areas are hypocellular and contain more mixoid tissue with high water content[ 18 , 25 ], which can be cystic, haemorrhagic, calcified and even ossified[ 5 , 24 ]. In the present study, some areas of the tumour were ossified, and a true metaplastic bone formation could be seen, with the presence of bone lamellae and osteoblasts, just as reported by Gurzu et al[ 26 ]. Schwannomas show strong immunoreactivity for S-100 protein, while CD34, CD117, DOG-1 and SMA are negative[ 27 ].…”

Extensive Abdominal Wall Incisional Heterotopic Ossification Reconstructed with Component Separation and Strattice Inlay

“… 1 There is a predilection for upper midline incisions; however, symptomatic heterotopic ossification of the abdominal wall seems to be much less common, with only single cases and small case series reported. 2 – 5 …”

“…Heterotopic ossification is known by many names: myositis ossificans circumscripta, ossifying pseudotumor, fibrodysplasia ossificans traumatica, neurogenic ossifying fibromyopathy, etc. 2 Osseous histological structure differentiates it from heterotopic calcification. The cause of heterotopic ossification is unknown, but 2 main theories exist: seeding of periosteal cells from nearby structures such as the xiphoid into the wound or osseous differentiation from pluripotent mesenchymal cell.…”

“…So far, recommendations for treatment have been excision and primary closure 2 , 4 with the possible addition of radiation treatment in the case of recurrence. 3 …”