Unique Morphologic Features of a Case of Hermansky-Pudlak Syndrome in the Colon: Extensive Mucosal Lipofuscin Pigmented Histiocytes and Crohn’s-like Mucosal Granulomatous Colitis

Hermansky-Pudlak syndrome (HPS) is a rare, autosomal recessive disorder predominantly affecting individuals of Puerto Rican descent. It is characterized by oculocutaneous albinism, platelet storage pool deficiency, and lysosomal ceroid accumulation in tissues. Lysosomal dysfunction has been shown to be associated with pulmonary fibrosis and granulomatous colitis in HPS patients, accounting for a significant portion of morbidity and mortality in this population. Clinical and endoscopic gastrointestinal manifestations in HPS patients are similar to those of active Crohn’s disease, including abdominal pain, bleeding, fissures, fistulas, and perianal involvement. Histology reveals granulomatous colitis that can be difficult to distinguish from Crohn’s disease. Identifying distinct morphologic features from Crohn’s disease is crucial for the diagnosis of HPS. Here, we present a case of a 27-year-old male with a history of HPS and refractory granulomatous colitis with severe perianal disease, who underwent total proctocolectomy and perianal excision. The unique, distinguishing morphologic features from Crohn’s disease in this case are: 1) grossly diffuse ulceration in the ano-rectum and cecum, 2) ulcerative and granulomatous inflammation predominantly involving the mucosa and submucosa of the colon, and 3) accumulation of ceroid pigment in the histiocytes of the lamina propria throughout the entire gastrointestinal tract. Immunohistochemical stains for CD3 and FoxP3-positive T cells in the granulomatous colitis were further analyzed. Thus, we fully document the extent of disease involvement and morphologic features in this patient and extensively discuss the similarities and differences between HPS and Crohn’s disease.