Intraosseous Pseudocarcinomatous Hyperplasia Associated With Chronic Osteomyelitis of the Mandible: Report of Two Cases

Pseudocarcinomatous Squamous Hyperplasia After Surgical Management Of Pediatric Ameloblastoma: An Immunohistochemical Study

Pseudocarcinomatous squamous hyperplasia (PSH) affecting the jaws is uncommon. The mandible is the most common location, usually as a complication associated with osteomyelitis, medication-related osteonecrosis or osteoradionecrosis. Herein, we report an 8-year-old male patient presenting a solid ameloblastoma, plexiform type, who was treated by segmental mandibulectomy with bone grafting. Three months later, on the underlying graft, a sinus tract was observed, and a small bone fragment was resected which was diagnosed as bone sequestration associated with PSH. After 7-year follow-up, the patient is well, without alterations. To our knowledge, for the first time, we report in detail the immunohistochemical features of PSH which, in addition to epithelial component profile and chronic inflammatory cells, revealed a diffuse infiltration by dendritic cells, suggesting that epithelial cell-immune cell interactions in PSH pathogenesis should also be considered.

Pseudocarcinomatous Squamous Hyperplasia Involving Bone: A Diagnostic Pitfall Mimicking Squamous Cell Carcinoma

BACKGROUND

Pseudocarcinomatous squamous hyperplasia (PSH) within the bone is uncommon and closely mimics well-differentiated squamous cell carcinoma (SCC). It arises from cutaneous or mucosal surfaces and grows directly into the bone. This study analyzes a large series of PSH and discusses the clinicopathologic features that facilitate its distinction from SCC.

DESIGN

Cases were identified from the surgical pathology files between 1985 and 2020.

RESULTS

The 31 cases included 21 males, 9 females, 1 unknown sex; who were 20 to 87 years old (average: 59 y). Sites included mandible-17, maxilla-5, toes-4, and 1 case from finger, femur, tibia, ischium, and unknown. Fourteen patients had a history of SCC, 13 treated with resection and chemoradiation and developed infected osteoradionecrosis, 4-medication-related osteonecrosis, 3-peripheral vascular disease, and diabetes mellitus, 3-trauma, 3-osteomyelitis, 3-unknown, and 1-hematologic malignancy. All cases exhibited severe osteomyelitis and nests of reactive keratinizing squamous epithelium that matured towards the bone surface, lacked significant atypia, or mitotic activity but permeated the medullary cavity. Patients with previous SCC developed PSH after 2 months to 8 years (average: 4 y). Nineteen of 30 patients had follow-up (2 to 48 mo, average: 17 mo); 6 patients experienced repeated debridements over 2 months to 1 year; no patient developed SCC.

CONCLUSIONS

PSH involving bone is infrequent, complicates severe osteomyelitis, and is often therapy related. The clinical findings are usually not concerning for malignancy, however, the histologic findings are an important diagnostic pitfall because they mimic SCC.

Mandibular intraosseous pseudocarcinomatous hyperplasia: a case report

Background

Mandibular pseudocarcinomatous hyperplasia is a rare and generally benign pathology. We report on one of these rare cases.

Case presentation

The case history of a 73-year-old white man stated that he had a carcinoma of the oropharynx, which was primarily treated with radiotherapy and chemotherapy 4 years prior. As a result of radiotherapy he developed an osteoradionecrosis of his mandible and a consecutive pathological fracture of his left mandibular angle. Subsequent osteosynthesis was performed with a reconstruction plate. When we first saw him, his reconstruction plate was partially exposed with intraoral and extraoral fistulation. The resected bone of his defect-bordering jaw showed the typical pathohistological findings of an intraosseous mandibular pseudocarcinomatous hyperplasia. After a first reconstruction attempt with an iliac crest graft failed, definitive reconstruction of his mandible with a microvascular anastomosed fibula graft was achieved.

Conclusions

Intraosseous pseudocarcinomatous hyperplasia of the mandible is a rare differential diagnosis in maxillofacial surgery. Besides other benign epithelial neoplasms, such as calcifying epithelial odontogenic tumor, squamous odontogenic tumor, or different forms of ameloblastoma, the far more frequent invasive squamous cell carcinoma needs to be excluded. A misinterpretation of pseudocarcinomatous hyperplasia as squamous cell carcinoma must be avoided because it can lead to a massive overtreatment.