Patients with primary cutaneous lymphoma are at risk for severe COVID-19. Data from the Spanish Primary Cutaneous Lymphoma Registry.

Conflict of interest

None to declare.

Dear Editor,

While some papers report an increased risk of COVID‐19 and worse outcomes in oncological patients, others have found no differences.

We are not aware of studies assessing risk for COVID‐19 and clinical outcomes of patients with Primary Cutaneous Lymphomas (PCL).

The objectives of our study were to evaluate the incidence of COVID‐19 and severe outcomes in a cohort of PCL patients, compare it to the general population, and describe changes in lymphoma staging 8 weeks after COVID‐19.

Registro Español de Linfomas Cutaneos (RELC) is a prospective cohort recruiting all patients with PCL referred to the 27 participating dermatology departments. In May 2020, we collected all patients with COVID‐19 and described their clinical data and evolution. We defined COVID‐19 cases, according to the European Centre for Disease Prevention and Control, as possible, probable or confirmed. COVID‐19 outcomes included asymptomatic or mild, hospitalized, intensive care unit (ICU) and deaths.

We estimated cumulative incidences, 95% Confidence Intervals (CI), and standardized incidence ratios (SIR) by age, sex and geographical area corresponding to the same period (January–November 2020) of Spanish figures published by the Spanish Ministry of Health. This study was approved by the ethics committee of Hospital 12 de Octubre (CEIM 20/297).

RELC included 1542 patients [56% Mycosis fungoides/Sézary (MF/SS), 44% nonMF/SS primary cutaneous lymphomas]. 20% were in T3 and T4 stages. Sixty patients (3.9%) suffered from COVID‐19, median age of 59.1 years (SD = 13.1); 50% of them are MF/SS, and 50% are nonMF/SS. Forty‐two patients had a microbiologically confirmed infection (70%), seven of them being probable cases (12%) and 11 possible cases (18%). Most patients (65%) experienced mild disease, 25% required hospitalization, 5% needed ICU and 5% died. 82% of patients reported stability of their PCLs, 9% improvement and 9% worsening.

Table 1 describes age‐specific cumulative incidences of COVID‐19 and COVID‐19 related events and compares them with the general population by means of the overall SIRs. None of the SIRs is statistically significant, but they increase with the severity of COVID‐19 disease. Patients in the 60–69 years stratum show a strongly increased risk of hospitalization [SIR: 4.81 (95% CI: 2.2–9.12)] and need for intensive care [SIR: 12.41 (95% CI: 1.5–45)]. In patients surviving, the oncological disease remains stable.

Table 1

Age‐specific cumulative incidence and Standardized Incidence Ratio of COVID‐19 incidence and COVID‐19 events in patients with cutaneous lymphomas compared with the equivalent definition in the general population of Spain

	COVID‐19 cases observed in Spain	Population in the provinces where RELC is established	Cumulative Incidence of COVID‐19 in Spain 95% CI (per 100 000 persons)	Observed cases in RELC	Expected cases	Adjusted Cumulative Incidence of COVID‐19 and 95% CI (per 100 000 persons)	SIR† 95% CI
All PCR confirmed cases vs Spanish confirmed cases (Only provinces where RELC is established)
All ages	906 160	23 874 765	3795 (3788–3803)	42	55.0	2900 (2089–3922)	0.76 (0.55–1.03)
10–49	521 362	13 422 094	3884 (3874–3895)	10	12.6	3022 (1439–5578)	0.8 (0.38–1.46)
50–59	142 436	3 862 125	3688 (3669–3707)	8	12.2	2497 (1066–4944)	0.66 (0.28–1.3)
60–69	91 777	2 904 159	3160 (3140–3181)	18	13.9	4907 (2902–7770)	1.29 (0.77–2.04)
≥70	150 585	3 686 387	4085 (4064–4106)	6	17.5	1302 (469–2852)	0.34 (0.13–0.75)
PCR Hospitalized cases vs Spanish hospitalized cases (Only provinces where RELC is established)
All ages	123 554	23 874 765	518 (515–520)	17	12.6	698 (406–1120)	1.35 (0.79–2.16)
10–49	22 537	13 422 094	168 (166–170)	3	1.7	885 (167–2620)	1.71 (0.35–5)
50–59	19 107	3 862 125	495 (488–502)	1	0.6	315 (0–1807)	0.61 (0.02–3.39)
60–69	21 957	2 904 159	756 (746–766)	9	4.8	2487 (1128–4741)	4.81 (2.2–9.12)
≥70	59 953	3 686 387	1626 (1613–1639)	4	1.7	879 (229–2272)	1.7 (0.46–4.35)
PCR ICU cases vs Spanish ICU cases (Only provinces where RELC is established)
All ages	9939	23 874 765	42 (41–42)	3	1.1	111 (21–328)	2.66 (0.55–7.77)
10–49	1512	13 422 094	11 (11–12)	0	NA	–	–
50–59	2029	3 862 125	53 (50–55)	1	0.1	291 (0–1665)	6.98 (0.18–39.0)
60–69	3126	2 904 159	108 (104–111)	2	0.2	517 (49–1899)	12.41 (1.5–45)
≥70	3272	3 686 387	89 (86–92)	0	NA	–	–
PCR death cases vs Spanish death cases (Only provinces where RELC is established)
All ages	28 624	23 874 765	120 (119–121)	2	3.56	67 (6–248)	0.56 (0.07 –2.03)
10–49	446	13 422 094	3 (3–4)	0	NA	–	–
50–59	1031	3 862 125	27 (25–28)	0	NA	–	–
60–69	2644	2 904 159	91 (88–95)	2	0.4	557 (53–2048)	4.65 (0.56–17.0)
≥70	24 503	3 686 387	665 (656–673)	0	NA	–	–

From January 2020 to 30 November 2020. Statistically significant results in bold.

ICU, Intensive care unit; PCR, Polymerase chain reaction test confirmed cases; RELC, Spanish Primary Cutaneous Lymphoma Registry.

SIR, Standardized Incidence Ratio by age‐sex and province.

There were limited data regarding PCL and COVID‐19. The United States CL Consortium and the EORTC CLTF established some general recommendations for the treatment of PCLs during the COVID‐19 pandemic , while some authors suggested that PCL does not increase the risk of SARS‐CoV‐2. As far as we know, this study is the first to describe the incidence and severity of COVID‐19 among PCL patients.

The strengths of our study are that it’s based on a previously defined and closely followed prospective cohort, and has comparable data for the general population. Few cases remained unnoticed because it is unlikely that COVID‐19 were diagnosed in a different setting.

Nevertheless, our study couldn't reach high statistical power, because the number of COVID‐19 outcomes was relatively low, especially for severe outcomes and death, and the elderly were less represented in RELC, probably due to reduced survival after disease.

We could not detect increased risks in all PCL patients compared to the general population, especially for rare outcomes such as mortality. However, we found an augmented risk of severe disease compared to the general population among those of 60 to 69 years of age (this group included more patients and outcomes, thus, offering more statistical power). The insufficient number of total cases didn't allow us further subdivision of the PCL group.

Our study suggests that PCL patients should be considered at risk for severe COVID‐19, requiring reinforced preventive measures and prioritization in vaccination strategies.

Funding sources

The Spanish Primary Cutaneous Lymphoma Registry (RELCP) is promoted by the Fundación Piel Sana Academia Española de Dermatología y Venereología, which received an unrestricted grant support from Kyowa Kirin Limited, United Kingdom. Collaborating pharmaceutical companies were not involved in the design and conducting of the study; collection, management, analysis and interpretation of data; preparation, review or approval of the manuscript; or the decision to submit the manuscript for publication.