# Cutaneous Neufibroma in the Absence of Classical NF1 Features: A Case Report and Literature Review

## TL;DR

A man with multiple skin growths but no other signs of NF1 raises questions about how the disease is diagnosed.

## Contribution

This case highlights the diagnostic challenge of atypical NF1 presentations with isolated cutaneous neurofibromas.

## Key findings

- A 47-year-old male presented with multiple cutaneous neurofibromas but lacked other classical NF1 features.
- The case suggests the possibility of mosaic NF1 or a minor phenotypic variation.
- Current diagnostic criteria may be insufficient for atypical adult-onset NF1 cases.

## Abstract

Neurofibromatosis type 1 (NF1) is a prevalent neurocutaneous illness resulting from mutations in the NF1 gene, usually diagnosed according to clinical criteria set by the National Institutes of Health (NIH). These encompass café-au-lait macules, axillary freckling, Lisch nodules, ocular gliomas, osseous lesions, neurofibromas, and familial history. Atypical instances exhibiting partial or isolated characteristics, such as numerous cutaneous neurofibromas (cNFs) absent other classical manifestations, provide a diagnostic difficulty and may be little acknowledged in clinical environments. We describe a 47-year-old male with several soft, non-tender, pinkish-red papules and nodules dispersed throughout the face, torso, limbs, and back. A solitary café-au-lait macule measuring 3 x 2 cm was seen below the right breast, no axillary or inguinal freckling was observed, Lisch nodules were absent during ophthalmologic examination, and there was no pertinent family history. The histopathological examination of a skin lesion verified the diagnosis of cutaneous neurofibroma. According to the NIH guidelines, the patient did not satisfy the requirements for a conclusive diagnosis of NF1. This instance underscores the clinical intricacy of NF1 spectrum diseases and suggests the potential for mosaic NF1 or a minor phenotypic variation. The existence of several cNFs without systemic involvement undermines the adequacy of existing diagnostic paradigms, particularly in adults who exhibit no early-life signs. The psychosocial challenges linked to widespread cNF distribution highlight the necessity for a comprehensive assessment. Limitations encompass the lack of genetic testing, which would have facilitated the confirmation of the diagnosis and the assessment of probable mosaicism. Isolated cutaneous neurofibromas, devoid of other conventional NF1 characteristics, are an uncommon yet clinically pertinent manifestation. Clinicians must uphold a heightened level of suspicion for aberrant NF1 phenotypes and contemplate further examination, using molecular diagnostics where feasible. Reevaluating diagnostic criteria to include these polymorphisms is essential for prompt identification, effective care, and enhanced patient outcomes.