A 52 year old patient presents with restricted or limited mouth opening. The patient has loss of attached gingiva and multiple areas of gingival recession and tight skin. A panoramic radiograph shows diffuse widening of the periodontal ligament. What is the most likely diagnosis?

Progressive systemic sclerosis

Hyperparathyroidism.

Cicatricial pemphigoid.

Erythema multiforme.

Advanced adult periodontitis.