Table 3.
Histopathological features of cutaneous manifestations found in patients with COVID‐19
| Study | Clinical form | Main histopathological features |
| Fernandez‐Nieto10 | Urticarial rash | Upper dermal oedema |
| Perivascular infiltrate of lymphocytes and some eosinophils | ||
| Amatore16 | Urticarial figurate lesions | Lichenoid and vacuolar interface dermatitis |
| Mild spongiosis and dyskeratotic basal keratinocytes | ||
| Papillary dermal oedema with superficial perivascular lymphocytic infiltrate and occasional neutrophils | ||
| Ahouach22 | Erythematous maculopapular rash | Slight spongiosis and basal cell vacuolation |
| Mild perivascular lymphocytic infiltrate | ||
| Gianotti27 | Erythematous eruption | Superficial perivascular dermatitis with slight lymphocytic exocytosis |
| Presence of a small thrombus in a vessel in the mid dermis | ||
| Swollen thrombosed vessels with neutrophils, eosinophils and nuclear debris patchily distributed in the dermis | ||
| Erythematous papular exanthem | Superficial and deep perivascular dermatitis | |
| Cuffs of lymphocytes surrounding blood vessels in a vasculitic pattern | ||
| In the mid dermis extravasated red blood cells from damaged vessels | ||
| Erythematous papular eruption | Superficial perivascular vesicular dermatitis, with features reminiscent of Grover disease | |
| Focal acantholytic suprabasal clefts | ||
| Dyskeratotic and ballooning herpes‐like keratinocytes | ||
| Presence of a nest of Langerhans cells within the epidermis | ||
| Patchy bandlike infiltration with occasional necrotic keratinocytes and minimal lymphocytic satellitosis | ||
| In the dermis, swollen vessels, with dense lymphocyte infiltration, mixed with rare eosinophils | ||
| Sanchez26 | Papulosquamous eruption | Focal parakeratosis in the epidermis |
| Mild spongiosis, with a few spongiotic vesicles containing lymphocytes and Langerhans cells | ||
| Papillary dermal oedema with moderate superficial lymphohistiocytic infiltrate | ||
| Diaz‐Guimaraens25 | Maculopapular and petechial rash | Focal parakeratosis and isolated dyskeratotic cells |
| Focal papillary dermal oedema and superficial perivascular lymphocytic infiltrate | ||
| Extravasated red cells | ||
| No signs of thrombotic vasculopathy | ||
| Rivera‐Oyola15 | Erythematous maculopapular rash with purpuric evolution | Mild perivascular infiltrate of predominantly mononuclear cells in the superficial dermis |
| Scattered foci of hydropic changes in the epidermis and slight spongiosis | ||
| Minimal acanthosis and focal parakeratosis | ||
| Marzano34 | Varicella‐like lesions (n = 7) | Features compatible with viral exanthem |
| Recalcati41 | Targetoid nonacral lesions (n = 2) | Mild superficial perivascular dermatitis |
| Perniosis‐like lesions on the fingers (n = 2) | Diffuse dense dermal–hypodermal lymphoid infiltrate with a prevalent perivascular pattern | |
| Signs of endothelial activation | ||
| Kolivras30 | Chilblain‐like lesions | Epidermal basal vacuolar alteration and scattered necrotic keratinocytes |
| Superficial and deep lichenoid, perivascular and perieccrine infiltrate of lymphocytes and occasional plasma cells | ||
| Presence of some nuclear debris without neutrophils | ||
| Plump endothelial cells in the venules surrounded by lymphoplasmacytic infiltrate | ||
| Absence of intraluminal thrombi or fibrin within venule walls | ||
| Magro31 | Retiform purpura | Thrombogenic vasculopathy |
| Extensive necrosis of the epidermis and adnexal structures | ||
| Interstitial and perivascular neutrophilia with prominent leucocytoclasia (IHC: extensive deposits of C5b‐9 within the microvasculature) | ||
| Palmoplantar livedoid patches | Superficial vascular ectasia and occlusive arterial thrombus within the deeper dermis | |
| Absence of inflammation (IHC: extensive vascular deposits of C5b‐9, C3d and C4d throughout the dermis, with marked deposition in an occluded artery) | ||
| Livedo racemosa | Modest perivascular lymphocytic infiltrate in the superficial dermis along with deeper‐seated small thrombi within rare venules of the deep dermis, in the absence of a clear vasculitis (IHC: significant vascular deposits of C5b‐9 and C4d) |
IHC, immunohistochemical assessment.