Investigating the histopathological findings and immunolocalization of rickettsialpox infection in skin biopsies: A case series and review of the literature

Abstract

Background: Recognition of rickettsialpox infection on skin biopsy can be challenging. The histopathology is non-specific and inconsistently described. We assess classic histopathologic features in confirmed cases and review the literature. Methods:We searched for cases of "rickettsialpox" diagnosed between 2006 and 2018 with positive immunostaining for Spotted Fever Group Rickettsia species. Original slides were evaluated for vacuolar alterations, granulomatous inflammation, vasculitis, necrosis, fibrin thrombi, microvesiculation, papillary dermal edema, and extravasated red blood cells. All biopsies were stained for CD3, CD20, CD68, and myeloperoxidase.Results: Six biopsy specimens were compiled, three of which were sampled from vesiculopapules, one from a maculopapule, and two from eschars. Vacuolar alterations and vasculitis were present in all specimens (6/6; 100%). Granulomatous inflammation was present in five specimens (5/6; 83.3%). Fibrin thrombi and red blood cells were seen in 3/6 (50%) of specimens. The eschars showed necrosis of the epidermis and superficial dermis (2/6, 33.3%). Only one specimen showed intraepidermal vesiculation and papillary dermal edema (1/6; 16.7%). All six specimens showed perivascular infiltration with CD3+ T-cells, and low amounts of CD20+ B-cells and neutrophils.Five of the six specimens (83.3%) showed significant levels of CD68+ histiocytes. Conclusion:The histopathology of rickettsialpox infection is septic lymphocytic and granulomatous vasculitis. K E Y W O R D S biopsy, histopathology, HIV, human immunodeficiency virus, immunohistochemistry, Rickettsia akari, rickettsial infection, rickettsialpox, skin

Vesicular spotted fever due to Rickettsia parkeri simulates the clinicopathologic features of rickettsialpox

“… 9 Compared with vesicular eruptions and eschar, morbilliform or petechial exanthems are nonspecific among rickettsioses and demonstrate lymphocytic vasculitis. 3 , 9 …”

“…8 In contrast, rickettsialpox may demonstrate neutrophilic infiltrates in addition to these features. 9 Compared with vesicular eruptions and eschar, morbilliform or petechial exanthems are nonspecific among rickettsioses and demonstrate lymphocytic vasculitis. 3,9 Several laboratory tests can aid in the diagnosis of rickettsioses (Table II).…”

“…9 Compared with vesicular eruptions and eschar, morbilliform or petechial exanthems are nonspecific among rickettsioses and demonstrate lymphocytic vasculitis. 3,9 Several laboratory tests can aid in the diagnosis of rickettsioses (Table II). 3 Of these, PCR using patient tissue or blood specimens is species-specific.…”

Buerger’s Disease May be a Chronic Rickettsial Infection with Superimposed Thrombosis: Literature Review and Efficacy of Doxycycline in Three Patients

“…David H. Walker et al reported that CD68 + macrophages/dendritic cells that contained R. akari within the cytoplasm were observed in biopsy specimens of eschars [ 86 ]; a similar finding was also observed in tsutsugamushi disease [ 87 ]. In Mediterranean spotted fever, rickettsialpox, and R. slovaca infection, the infiltration of lymphocytes and macrophages are the main findings in eschars [ 88 89 90 ]. Thus, the early lesions of tsutsugamushi disease, rickettsial infections, and BD share similar histopathological features.…”

Cutaneous lymphohistiocytic infiltrates with foamy macrophages: A novel histopathological clue to Stenotrophomonas maltophilia septicemia

“…1 Cutaneous septic vasculitis may be observed secondarily to different bacterial infections, including Neisseria meningitidis, Neisseria gonorrhoeae, Pseudomonas aeurignosa, Staphylococcus aureus, as well as certain rickettsioses. [1][2][3][4][5][6][7][8] Depending on the infectious agent, the temporal evolution of the infection (acute vs subacute/chronic), and the host immune status, the ensuing histopathological picture may vary, featuring different combinations of (a) inflammatory leukocytoclastic vasculitis, (b) occlusive thrombosis of small vessels, and (c) subepidermal or intraepidermal pustulation. 1,3,5 The term "septic vasculopathy" has been used for cases showing vascular occlusive phenomena prevailing over the inflammatory vasculitic component.…”