Location
Suwanee, GA
Start Date
6-5-2025 1:00 PM
End Date
6-5-2025 4:00 PM
Description
Introduction: Multicentric reticulohistiocytosis (MRH) is a rare systemic autoimmune disorder characterized by skin and joint involvement. It classically presents with symmetric erosive polyarthritis and papulonodular skin lesions and is frequently associated with underlying malignancies. MRH has fewer than 300 cases reported in medical literature worldwide since its first report in 1937, but studies suggest that approximately 25-30% of patients diagnosed with MRH have underlying malignancy. Because of its paraneoplastic nature, it is recommended that patients diagnosed with MRH promptly undergo cancer screening.
Case Presentation: In this case report, a 58 year-old male presented to the dermatology clinic complaining of a pruritic and painful rash along with numerous aching joints. His symptoms began after he was exposed to an insecticide and worsened with direct sunlight, heat, and sweat. Physical examination revealed brightly erythematous, smooth papules and nodules of the knees, elbows, and dorsal hands, red-orange dermal papules coalescing into plaques on the upper chest and back, and indurated waxy papules and plaques of the pinnae and nares. Labs were unremarkable aside from elevated monocytes on a complete blood count with a differential. Shave biopsy was performed and pathology revealed a dermal nodule of epithelioid histiocytes and scattered giant cells with pink “ground glass”-like cytoplasm. PAS and AFB stains were negative. A diagnosis of multicentric reticulohistiocytosis was made and treatment was started with corticosteroids, methotrexate, and alendronate.
Discussion: MRH is a rare autoimmune histiocytic disorder with arthropathic features similar to that seen in rheumatoid arthritis (RA). For this reason, oftentimes pharmacologic agents given in RA are also prescribed in MRH. Accurate diagnosis is dependent on histology, so biopsy of skin lesions must be taken and sent to pathology. In addition to various cancers, tuberculosis (TB) is found in approximately 5% of MRH which necessitates ordering an interferon-gamma release assay. Fortunately, both the tuberculosis and malignancy diagnostic evaluations were negative for the patient. A literature review yielded no association of MRH and the insecticide the patient used.
Conclusion: While an uncommon entity, MRH is important to keep in mind when a patient with arthritic symptoms and papulonodular lesions presents due to its strong association with malignancies and increased risk of concomitant tuberculosis. If RA and MRH are both diagnostic considerations, a biopsy of a nodule must be taken to ensure an accurate diagnosis. These patients require management from a rheumatologist and oncologist, highlighting the need for multidisciplinary treatment.
Embargo Period
5-28-2025
Included in
Coral Beads and Ground Glass: A Case of Multicentric Reticulohistiocytosis
Suwanee, GA
Introduction: Multicentric reticulohistiocytosis (MRH) is a rare systemic autoimmune disorder characterized by skin and joint involvement. It classically presents with symmetric erosive polyarthritis and papulonodular skin lesions and is frequently associated with underlying malignancies. MRH has fewer than 300 cases reported in medical literature worldwide since its first report in 1937, but studies suggest that approximately 25-30% of patients diagnosed with MRH have underlying malignancy. Because of its paraneoplastic nature, it is recommended that patients diagnosed with MRH promptly undergo cancer screening.
Case Presentation: In this case report, a 58 year-old male presented to the dermatology clinic complaining of a pruritic and painful rash along with numerous aching joints. His symptoms began after he was exposed to an insecticide and worsened with direct sunlight, heat, and sweat. Physical examination revealed brightly erythematous, smooth papules and nodules of the knees, elbows, and dorsal hands, red-orange dermal papules coalescing into plaques on the upper chest and back, and indurated waxy papules and plaques of the pinnae and nares. Labs were unremarkable aside from elevated monocytes on a complete blood count with a differential. Shave biopsy was performed and pathology revealed a dermal nodule of epithelioid histiocytes and scattered giant cells with pink “ground glass”-like cytoplasm. PAS and AFB stains were negative. A diagnosis of multicentric reticulohistiocytosis was made and treatment was started with corticosteroids, methotrexate, and alendronate.
Discussion: MRH is a rare autoimmune histiocytic disorder with arthropathic features similar to that seen in rheumatoid arthritis (RA). For this reason, oftentimes pharmacologic agents given in RA are also prescribed in MRH. Accurate diagnosis is dependent on histology, so biopsy of skin lesions must be taken and sent to pathology. In addition to various cancers, tuberculosis (TB) is found in approximately 5% of MRH which necessitates ordering an interferon-gamma release assay. Fortunately, both the tuberculosis and malignancy diagnostic evaluations were negative for the patient. A literature review yielded no association of MRH and the insecticide the patient used.
Conclusion: While an uncommon entity, MRH is important to keep in mind when a patient with arthritic symptoms and papulonodular lesions presents due to its strong association with malignancies and increased risk of concomitant tuberculosis. If RA and MRH are both diagnostic considerations, a biopsy of a nodule must be taken to ensure an accurate diagnosis. These patients require management from a rheumatologist and oncologist, highlighting the need for multidisciplinary treatment.