Squamous cell carcinoma, keratoacanthoma-type; Prurigo nodularis; This literature-non-study case was reported in a literature article and describes the occurrence of KERATOACANTHOMA (Squamous cell carcinoma, keratoacanthoma-type) in an 86-year-old male patient who received mRNA-1273 (Moderna COVID-19 Vaccine) for COVID-19 prophylaxis. The occurrence of additional non-serious events is detailed below.      No Medical History information was reported.  On 02-Mar-2021, the patient received second dose of mRNA-1273 (Moderna COVID-19 Vaccine) (unknown route) 1 dosage form. On 16-Mar-2021, the patient experienced KERATOACANTHOMA (Squamous cell carcinoma, keratoacanthoma-type) (seriousness criterion medically significant). In 2021, the patient experienced NEURODERMATITIS (Prurigo nodularis). The patient was treated with 5-FLUOROURACIL [FLUOROURACIL] (intralesional) in 2021 for Keratoacanthoma, at a dose of 1.5 milliliter once a week; CLOBETASOL in 2021 at an unspecified dose and frequency and Surgery (Mohs surgery) for Keratoacanthoma. In 2021, KERATOACANTHOMA (Squamous cell carcinoma, keratoacanthoma-type) had resolved. At the time of the report, NEURODERMATITIS (Prurigo nodularis) outcome was unknown.      DIAGNOSTIC RESULTS (normal ranges are provided in parenthesis if available): In March 2021, Biopsy skin: Shave biopsy of the left calf 1 week later demonstrated a well-differentiated keratoacanthoma-type squamous cell carcinoma. In August 2021, Biopsy skin: The patient then presented to our clinic in August 2021, at which point 2 scallop biopsies were taken from the right pretibial area. The pathology results were consistent with SCC, keratoacanthoma type. Skin biopsy demonstrated atypical keratinocytes replacing the full thickness of normal epithelium. Cells with large hyperchromatic and atypical nuclei were seen at all levels. Atypical keratinocytes extend into the dermis as small islands. Scattered mitotic figures were also observed. A hematoxylin and eosin stain was used.   For mRNA-1273 (Moderna COVID-19 Vaccine) (Unknown), the reporter did not provide any causality assessments.   No concomitant medications were reported.  On 16-Mar-2021, patient began to experienced severe pruritus of the lower pretibial area, and within 2 days and noticed red nodules on the bilateral legs (7 on the right and 4 on the left). Prior to 16-Mar-2021, he did not experience any previous cutaneous signs or symptoms that were concerning for keratoacanthomas on the bilateral legs.  There were 11 other similar lesions at the time of initial presentation.  However, none were biopsied. There were no lesions at the vaccination site. The lesion was cleared via Mohs surgery in 2 stages; however, the area was complicated by infection and required almost 2 months to heal.  The remainder of the eruption was diagnosed as prurigo nodularis, and the patient was prescribed a clobetasol ointment, with minimal improvement.  Given the numerous lesions, he was treated with intralesional 5-fluorouracil with resolution over a 6-week period. Initially, the right leg was treated, requiring 3 weeks of treatment. Afterward, the left leg was treated, also requiring 3 weeks of treatment.  Author concluded that patient did not have any new or known risk factors for the development of eruptive keratoacanthomas on the bilateral legs, clinicians should be aware of Moderna COVID-19 vaccine-induced keratoacanthomas-a novel finding-as a potential occurrence following vaccination with the mRNA vaccine. As with any individual case report, author acknowledge the limitation of this report in determining the causation of eruptive keratoacanthomas following COVID-19 vaccination. However, this case will contribute to the limited clinical data on cutaneous, adverse COVID-19 vaccine side effects. Further reports and studies of any additional cases will be important for investigating the incidence and pathophysiology of this potential adverse reaction.  Company comment: This literature-non-study case concerns an elderly male patient aged 86 years with no medical history of cutaneous lesions in the past reported, who experienced the unexpected serious (medically significant) event of Keratoacanthoma (reported as Squamous cell carcinoma, keratoacanthoma-type), and unexpected non-serious event of Neurodermatitis about 2 weeks after second dose of mRNA-1273 vaccine in covid-19 vaccination series. Patient had severe pruritus of the lower pretibial area about 2 weeks after vaccination, which was followed by red nodules on the bilateral legs (7 on the right and 4 on the left) within two days. A shave biopsy of the left calf 1 week later demonstrated a well-differentiated keratoacanthoma-type squamous cell carcinoma (SCC). There were 11 other similar lesions at the time of initial presentation which were not biopsied. And also there were no lesions at the vaccination site. The lesion was cleared via Mohs surgery in 2 stages; however, the area was complicated by infection and required almost 2 months to heal. The remainder of the eruption was diagnosed as prurigo nodularis, and patient was prescribed a clobetasol ointment, with minimal improvement. After about three months, 2 scallop biopsies were taken from the right pretibial area and histopathology was consistent with SCC, keratoacanthoma type. Given the numerous lesions, the patient was treated with intralesional 5-fluorouracil with resolution over a 6-week period, that is, the patient was treated with 1.5 mL of 50-mg/mL 5-fluorouracil, which was injected intralesionally into each growth once per week for 6 weeks. Initially, the right leg was treated, requiring 3 weeks of treatment. Afterward, the left leg was treated, also requiring 3 weeks of treatment. The benefit-risk relationship of mRNA-1273 is not affected by this report.   Most recent FOLLOW-UP information incorporated above includes: On 22-Dec-2022: Follow-up received by safety on 23-Dec-2022 has Email with FTA and contains significant information: Reporter information, literature information, lab data, suspect product details, treatment drugs and event information were updated.; Sender's Comments: This literature-non-study case concerns an elderly male patient aged 86 years with no medical history of cutaneous lesions in the past reported, who experienced the unexpected serious (medically significant) event of Keratoacanthoma (reported as Squamous cell carcinoma, keratoacanthoma-type), and unexpected non-serious event of Neurodermatitis about 2 weeks after second dose of mRNA-1273 vaccine in covid-19 vaccination series. Patient had severe pruritus of the lower pretibial area about 2 weeks after vaccination, which was followed by red nodules on the bilateral legs (7 on the right and 4 on the left) within two days. A shave biopsy of the left calf 1 week later demonstrated a well-differentiated keratoacanthoma-type squamous cell carcinoma (SCC). There were 11 other similar lesions at the time of initial presentation which were not biopsied. And also there were no lesions at the vaccination site. The lesion was cleared via Mohs surgery in 2 stages; however, the area was complicated by infection and required almost 2 months to heal. The remainder of the eruption was diagnosed as prurigo nodularis, and patient was prescribed a clobetasol ointment, with minimal improvement. After about three months, 2 scallop biopsies were taken from the right pretibial area and histopathology was consistent with SCC, keratoacanthoma type. Given the numerous lesions, the patient was treated with intralesional 5-fluorouracil with resolution over a 6-week period, that is, the patient was treated with 1.5 mL of 50-mg/mL 5-fluorouracil, which was injected intralesionally into each growth once per week for 6 weeks. Initially, the right leg was treated, requiring 3 weeks of treatment. Afterward, the left leg was treated, also requiring 3 weeks of treatment. The benefit-risk relationship of mRNA-1273 is not affected by this report.