[Malignant nail tumors]

The Diagnosis and Treatment of Nail Disorders

BACKGROUND

Nail disorders can arise at any age. About half of all nail disorders are of infectious origin, 15% are due to inflammatory or metabolic conditions, and 5% are due to malignancies and pigment disturbances. The differential diagnosis of nail disorders is often an area of uncertainty.

METHODS

This review is based on publications and guidelines retrieved by a selective search in PubMed, including Cochrane reviews, meta-analyses, and AWMF guidelines.

RESULTS

Nail disorders are a common reason for derma - tologic consultation. They are assessed by clinical inspection, dermatoscopy, diagnostic imaging, microbiological (including mycological) testing, and histopathological examination. Some 10% of the overall population suffers from onychomycosis, with a point prevalence of around 15%. Bacterial infections of the nails are rarer than fungal colonization. High-risk groups for nail disorders include diabetics, dialysis patients, transplant recipients, and cancer patients. Malignant tumors of the nails are often not correctly diagnosed at first. For subungual melanoma, the mean time from the initial symptom to the correct diagnosis is approximately 2 years; this delay is partly responsible for the low 10-year survival rate of only 43%.

CONCLUSION

Evaluation of the nail organ is an important diagnostic instrument. Aside from onychomycosis, which is a common nail disorder, important differential diagnoses such as malignant diseases, drug side effects, and bacterial infections must be considered.

Important malignant and new nail tumors

The nail apparatus is an integral part of the functional unit of the digital tip. Although overall uncommon, all cells and tissues occurring in this area can give rise to neoplastic lesions. Given the special anatomical location, such tumors frequently show morphological and symptom-related differences compared to similar lesions located elsewhere on the skin. Though particularly threatening, there is often a substantial delay in the diagnosis of Bowen's disease, ungual squamous cell carcinoma, and melanoma. Nevertheless, local excision with sufficient surgical margins is usually sufficient and superior to amputation of the distal phalanx. In recent years, a number of nail-specific tumors have been described. Tumors such as onychomatricoma, onychocytic matricoma, onychocytic carcinoma, and onychopapilloma originate from the nail matrix. Onycholemmal cysts, onycholemmal horn, and the proliferating onycholemmal tumor are characteristic nail bed tumors. Onycholemmal carcinoma is a slowly growing low-grade malignancy. Using modern diagnostic methods, careful examination - including biopsy and histopathology - of nail changes not responding to conservative treatment will help identify nail-specific neoplasms and prevent the progression of malignant nail tumors.

Bowen disease of the nail unit: a retrospective study of 12 cases and their association with human papillomaviruses

BACKGROUND

Bowen disease is the most frequent nail malignancy, usually seen as a verrucous plaque of the nail in men.

OBJECTIVE

To characterize the affected patient population, the clinical manifestations, the diagnostic delay and diagnostic steps, and presence of human papilloma virus (HPV) infection.

METHODS

We retrospectively evaluated all cases of Bowen disease of the nail unit over a period of 9 years. Data were obtained from our electronic database. Human papilloma virus genotype was assessed in biopsy specimens by polymerase chain reaction (PCR) sequencing.

RESULTS

We identified 12 cases of Bowen disease of the nail unit in 10 patients. Mean age at onset was 52 years, with a male predominance of 90%. The thumb and middle finger were the most frequently affected (66%). Fifty percent of the lesions presented as periungual and subungual verrucous tumours. Patients sought medical evaluation after a mean delay of 5.7 years; histopathological diagnosis was made after a mean delay of 3.2 years. HPV infection was identified in 75% of the cases.

CONCLUSIONS

Any recently appeared verrucous lesion of the nail unit in men above the age of 40 years should raise the suspicion of Bowen disease and lead to further histopathological diagnostic procedures.