TABLE 1.

Studies on cutaneous vascular manifestations of COVID‐19

Reference	Skin findings with vascular features	Pathological finding of vascular injury	Lab
Original articles
57	Livedoid lesions, perniosis, chilblain erythema, maculohemorrhagic rash	Vasodilation, endothelial swelling, perivascular infiltration of lymphocytes and eosinophils, microthrombosis, severe vascular damage, RBC extravasation	—
16	19% showed pseudo‐chilblain, 6% showed livedo/necrosis	—	—
58	Chilblain of the toes (more common) and fingers with mild pain and pruritus, all patients had good prognosis without any complications.	Skin biopsy was performed in six patients. The findings include perivascular and perieccrine lymphocytic infiltration with vasculopathy changes, dermal edema, RBC extravasation and thrombosis limited to the papillary dermis.	Chemistry and coagulation tests were normal, only elevated d‐dimer in one patient without any complication. RT‐PCR was positive only in one case.
59	Swelling and edema of the toes, erythemato‐violaceous macules and purpuric lesions, in video capillaroscopy: pericapillary edema, abnormal shape and dimension, microhemorrhages and capillary dilation	Dermal edema, RBC extravasation, superficial, and deep perivascular and perieccrine lymphocytic infiltration, endothelial swelling, fibrin thrombus, granular deposition of c3 in the vessel wall in DIF study	Negative RT‐PCR test, negative IgG antibody against the nucleocapsid protein of SARS‐CoV‐2 but positive for antibody against S1 spike protein of virus in some patients, other blood test were normal
60	Pernio‐like lesions (18%), retiform purpura (6.4%). Patients with pernio had better prognosis than patients with retiform purpura.	—	—
15	Acro‐ischemia that presented as acral cyanosis, skin bulla, and progression to dry gangrene	—	High d‐dimer, fibrinogen and FDP in all cases, prolonged PT and DIC in four cases. d‐dimer and FDP levels progressively elevated consistent with COVID‐2019 exacerbation.
Review articles
61	Petechial lesions, retiform purpura, livedoid lesions, acro‐ischemia, chilblain‐like lesions, urticarial vasculitis, Kawasaki‐like lesions	Superficial and deep perivascular infiltration of lymphocytes, endothelial swelling, fibrinoid necrosis, vascular thrombosis, leukocytoclastic vasculitis, RBC extravasation	—
62	The most commonly reported skin finding was chilblain‐like lesions (400, 40.1%), followed by maculopapular lesions (230, 23.1%), vesicular lesions (101, 10.1%), urticarial lesions (87, 21.8%), livedoid/necrotic lesions (23, 2.3%), and other/non‐descript rashes/skin lesions (197, 19.8%). Pain/burning was reported in at least 96 cases, and itch was reported in at least 268 cases.	—	—
63	Erythematous, urticarial, and vesicular (chicken pox‐like or varicelliform), Pete‐chiae rash, livedo reticularis, reactivation of oral herpes simplex virus type 1 (HSV‐1), vascular lesions and peculiar (perniosis‐like) skin lesions	—	—
64	Vascular complications including acro‐ischemia, livedo‐like necrosis, chilblain‐like eruptions	Histopathological investigations in three patients who died from COVID‐19 revealed hyaline thrombi in microvessels of skin.	—
Case series
65	Chilblain‐like acral lesion	Necrotic keratinocytes, dermal edema, perivascular and perieccrine lymphocytic infiltration, endothelialitis, microthromboses, fibrin deposition, immunoreactant deposits on vessels	—
66	Chilblain acral lesions	RBC extravasation, dermal edema, lymphocytic vasculitis, fibrinoid necrosis, microthrombosis, superficial and deep perivascular and perieccrine infiltration of lymphocytes with extension to subcutis tissue, SARS‐COV2 spike protein in the endothelial cells of vessels and epithelial cells of eccrine glands	Normal CBC, normal coagulation test, minimally elevated d‐dimer in one patient
67	Petechial and purpuric lesions (7.7%), necrosis (7.7%), pernio (1.9%). Skin manifestations were most commonly seen in elder patients (>55 y) with comorbidities.	—	—
68	Pernio‐like lesions in 318 (63%) of patients, 9.2% with associated acrocyanosis	Perivascular lymphocytic infiltration without vasculitis in five patients, small vessel lymphocytic vasculitis without microthrombosis in one patient, lymphocytic vasculitis with thrombosis in one patient	—
Case reports
69	Transient livedo reticularis several days after onset of COVID‐19	Not reported but they proposed microthrombosis as etiology of vascular cutaneous presentation of COVID‐19	—
70	Fever, respiratory distress and skin mottling (like sepsis induced cutaneous changes) in a newborn patient from the symptomatic mother	—	O2 sat: 93% CBC‐NL
17	Cutaneous features consistent with vaso‐occlusive or vasculopathicethiology, including retiform purpura with obvious inflammation, bulla formation and necrosis, chilblain‐like lesions in the acral sites or livedoid rash on the extremities in three cases	Histopathologic studies of the lung and skin of these patients indicated a microvascular injury with thrombosis and complement deposition in the vessel walls. Co‐localization of SARS‐CoV2‐specific spike glycoproteins with complement components in the lung and skin was also documented.	Mild thrombocytopenia (in two cases), high d‐dimer level (in three of five cases)
14	Erythematous‐violaceous lesions on the toes of a child with pruritus and burning, progressing to purpuric lesions with necrotic crust within a few days	—	—
Letter to Editor
71	Maculopapular exanthems were the most frequent manifestation observed (10). Pseudo‐chilblain (9), palpable purpura (4), and livedo reticularis (1)	Endothelial swelling, perivascular and periadnexal lymphocytic sometime neutrophilic infiltration, thrombosis	—
72	Retiform purpura with hemorrhagic blister and crust on the lower extremities, PTE during hospitalization	Thrombosis, deposition of IgM, C3, C9, and fibrinogen in the vessel wall	Elevated serum level of d‐dimer and acute phase reactant, leukopenia and after PTE, thrombocytopenia
73	Acro‐ischemia: purpuric lesions, hemorrhagic bullae and necrosis in the acrals	Small vessel vasculitis, RBC extravasation and neutrophil infiltration	Elevated CRP and d‐dimer level, leukocytosis with neutrophilia and lymphocytopenia, Plt and coagulation test were normal.
12	Petechial skin rash in one COVID‐19 patient mimicking other viral infections like dengue	—	—
Key findings: Cutaneous lesions with a vascular component including chilblain‐like lesions, retiform purpura, petechia, livedoreticularis, and skin necrosis are some of the most common and important manifestations of COVID‐19 patients. The most common findings in skin biopsy of these lesions are perivascular infiltration, vascular injury, and microthrombus formation. Various mechanisms have been proposed for these manifestations, including direct virus damage or immune system reactions. The relationship between the incidence of these lesions and the prognosis of COVID‐19 has not yet been definitively determined.

Abbreviations: CBC, complete blood count; CBC‐NL, complete blood count‐normal level; DIC, disseminated intravascular coagulation; DIF, differential; FDP, fibrinogen degradation product; PT, prothrombin time; PTE, pulmonary thromboembolism; RBC, red blood cells; RT‐PCR, reverse transcription polymerase chain reaction; SARS‐CoV‐2, severe acute respiratory syndrome coronavirus 2.