Canine histiocytic diseases: Histiocytic diseases in dogs are well recognized. They are a frustrating group of diseases because it may be difficult to differentiate them from granulomatous, reactive inflammatory or lymphoproliferative diseases.Raine syndrome: Raine syndrome (RNS), also called osteosclerotic bone dysplasia, is a rare autosomal recessive congenital disorder characterized by craniofacial anomalies including microcephaly, noticeably low set ears, osteosclerosis, a cleft palate, gum hyperplasia, a hypoplastic nose, and eye proptosis. It is considered to be a lethal disease, and usually leads to death within a few hours of birth.Orbital apex syndrome: Orbital apex syndrome, also known as Jacod syndrome, is a collection of cranial nerve deficits associated with a mass lesion near the apex of the orbit of the eye. This syndrome is a separate entity from Rochon–Duvigneaud syndrome, which occurs due to a lesion immediately anterior to the orbital apex.ExophthalmosHistiocyteVerruciform xanthoma: Verruciform xanthoma is an uncommon benign lesion that has a verruciform (wart-like) appearance, but it may appear polypoid, papillomatous, or sessile. Usually found on the oral mucosa of middle-aged persons, verruciform xanthomas have also been reported on the scrotum and penis of middle-aged to elderly Japanese males.Non-Langerhans cell histiocytosis: Non-Langerhans cell histiocytosis refers to a family of histiocytosis characterized by the absence of Langerhans cells.Multicentric reticulohistiocytosis: Multicentric reticulohistiocytosis is a multisystem disease beginning usually around the age of 50 years old, and is twice as common in women.Cerebellar stroke syndromeFibrin ring granuloma: A fibrin ring granuloma is a histopathological finding that is characteristic of Q fever. On hematoxylin-eosin staining, the fibrin ring granuloma consists of a central lipid vacuole (usually washed-out during fixing and staining, leaving only an empty hole) surrounded by a dense red fibrin ring and epithelioid macrophages.Gross examination