Molecular Profile of Subungual Melanoma: A MelaNostrum Consortium Study of 68 Cases Reporting BRAF, NRAS, KIT, and TERT Promoter Status

BACKGROUND

Subungual melanoma (SM) is an unusual type of melanocytic tumor affecting the nail apparatus. The mutational prevalence of the most prominently mutated genes in melanoma has been reported in small cohorts of SM, with unclear conclusions on whether SM is different from the rest of melanomas arising in acral locations or not. Hence, the molecular profile of a large series of SM is yet to be described.

OBJECTIVES

The aim of this study was to describe the molecular characteristics of a large series of SM and their association with demographic and histopathological features.

METHODS

Patients diagnosed with SM between 2001 and 2021 were identified from six Spanish and Italian healthcare centers. The mutational status for BRAF, NRAS, KIT, and the promoter region of TERT (TERTp) were determined either by Sanger sequencing or next-generation sequencing. Clinical data were retrieved from the hospital databases to elucidate potential associations.

RESULTS

A total of 68 SM cases were included. Mutations were most common in BRAF (10.3%) and KIT (10%), followed by NRAS (7.6%), and TERTp (3.8%). Their prevalence was similar to that of non-subungual acral melanoma but higher in SM located on the hand than on the foot.

CONCLUSIONS

To date, this study represents the largest cohort of SM patients with data on the known driver gene mutations. The low mutation rate supports a different etiopathogenic mechanism for SM in comparison of non-acral cutaneous melanoma, particularly for SM of the foot.

Subungual Glomus Tumor

Subungual glomus tumors arise from the glomus body of the digits. They are rare and benign and often in a single location. Their diagnosis relies on the typical clinical triad of symptoms and on imaging findings, mainly magnetic resonance imaging with gadolinium injection. Subungual tumors treatment is complete resection, essential for cure. The different surgical techniques aim to: a painless digit with normal range of motion and sensitivity, without nail deformity after tumour resection, and to recurrence prevention. They vary according to tumor location. Classic surgical approaches are: the nail unit sparing ones (para-ungual, lateral subperiosteal, periungual), and the nail unit non-sparing ones (all transungual approaches with nail bed splitting). In this paper, we review the literature for the different approaches describing the advantages and drawbacks of each of them. We also describe the author's preferred subperiosteal "shark mouth" flap containing the nail plate and the nail bed as a single unit. It can be performed whether the tumor is located centrally, peripherally, or under the germinal matrix with very satisfactory outcomes.

Non-subungual presentation of osteochondroma in toes-A case report with review of literature

A 23-year-old male presented with long-standing swelling in the middle of the third toe right side with difficulty in wearing footwear. Clinical examination revealed it as bony hard fixed swelling moving with interphalangeal joint movements. Clinical diagnosis of benign bony swelling was made and radiological investigation demonstrated features suggestive of osteochondroma. En-mass excision of the lesion was done, with histo-pathological confirmation of osteochondroma. Although the subungual presentation of osteochondroma or exostosis in toes is quite common, the astounding non-subungual presentation should also be kept in mind as a plausible differential diagnosis of benign bony swelling in toes.

Cellular Digital Fibroma: A Comprehensive Review of a CD34-Positive Acral Lesion of the Distal Fingers and Toes

Cellular digital fibroma is a benign fibrous lesion that typically occurred on either a finger or a toe. Cellular digital fibroma was introduced as a distinctive cluster of differentiation 34 (CD34)-positive lesion in July 2005. Cellular digital fibroma has been described in 20 patients: 12 men and 8 women. The patients ranged in age from 27 to 83 years old (median, 52 years old) at diagnosis. The tumor had been present from 2 months to 2 years (median, 11 months) prior to seeking medical attention. The cellular digital fibroma was usually slowly growing and asymptomatic; there has been no prior history of trauma at the tumor site. The lesion typically presented as either an erythematous or a flesh-colored, solitary papule of 5 mm or smaller. It frequently occurred on either the dorsal, lateral or ventral side of a digit. Yet, some of the lesions were located on the nail fold of the digit. Cellular digital fibroma shows a prominent cellular proliferation of spindle-shaped fibroblasts, without any atypia or mitoses, that extends from the papillary into the upper reticular dermis; diffuse and strongly positive CD34 staining is present throughout the entire tumor. There is no erosion by the tumor of the bony phalanx. Other acral tumors, such as superficial acral fibromyxoma (which also has diffuse strongly positive CD34 staining) and acquired digital fibrokeratoma (which is either CD34-negative or only focal CD34 positive), are in the clinical and pathologic differential diagnosis of cellular digital fibroma. Conservative complete excision is the treatment of cellular digital fibroma; however, even for tumors that have only been partially removed during biopsy, recurrence has not been observed. In conclusion, cellular digital fibroma is a unique CD34-positive acral lesion of the distal fingers and toes whose diagnosis requires correlation of the clinical morphology and the pathologic features of the tumor.

Extensive Perineural Spread of Subungual Melanoma

BACKGROUND

Subungual melanoma (SUM) is a rare form of melanoma confined to the nailbed and is rarely of the desmoplastic subtype. The often subtle nature of SUM, initially starting as a small dark spot or line in the nailbed, means deeper invasion can occur before a patient seeks clinical evaluation for a large, ulcerated lesion. We report the only known case of perineural spread of SUM of the lower extremity and describe its extensive path of perineural spread from the toe.

CASE DESCRIPTION

A 72-year-old man with a distant history of SUM status post second ray amputation, presented for evaluation of ipsilateral foot drop. Imaging revealed nodular involvement of tibial, peroneal, and sciatic nerves. Biopsies revealed desmoplastic melanoma and he was treated with nivolumab.

CONCLUSIONS

We report the only known case of perineural spread of SUM of the lower extremity and describe the pathoanatomy of perineural spread. A high index of suspicion for recurrent disease should be maintained even many years after completion of treatment.

A Growing Mass under the Nail: Subungual Eccrine Poroma

Eccrine poroma is a benign adnexal tumour, which originates from the acrosyringium of eccrine sweat glands. Eccrine poroma is an uncommon neoplasm, the typical clinical presentation of which is a solitary soft sessile reddish papule protruding from a cup-shaped shallow depression. Many challenges remain in the diagnosis of eccrine poroma because it does not always present with classical features and may mimic any other cutaneous benign and malignant lesions. Eccrine poromas may occur on any skin surface with sweat glands; on the other hand, the most common sites of involvement include the palms and soles, which are rich in eccrine sweat glands. Here, we present a case of subungual eccrine poroma, which is an extremely rare presentation of poromas. We also highlight dermoscopic features of eccrine poroma and review the available literature on the subject.

Painful tumors in a patient with neurofibromatosis type 1: a case report

BACKGROUND

Herein, we report an unusual case of multifocal glomus tumors in the same hand in a patient suffering from neurofibromatosis type 1.

CASE PRESENTATION

The patient was a 37-year-old Moroccan woman, suffering from neurofibromatosis type 1, with intense pain in the fingers, successfully treated with the excision of the tumors. Histology of the lesions confirmed the diagnosis of glomus tumor.

CONCLUSION

We present this case to support the association between glomus tumors and neurofibromatosis type 1. Thus, we strongly recommend that one should suspect a glomus tumor in patients with neurofibromatosis type 1 if such patients have symptoms from finger pulp or nails.

Subungual Solitary Angiokeratoma Simulating a Squamous Cell Carcinoma

Subungual angiokeratoma is extremely rare. Only 1 case is reported in the literature, presenting as a longitudinal pigmented band on a toenail. We report a case of a subungual angiokeratoma on a fingernail of a 43-year-old woman, clinically mimicking a squamous cell carcinoma. Medical imaging revealed a soft tissue tumor and erosion of the distal phalanx. Although extremely rare, solitary angiokeratomas may arise in the nail apparatus and should be added to the differential diagnosis of subungual warty tumors.

Polydactylous Transverse Erythronychia: Report of a Patient with Multiple Horizontal Red Bands Affecting the Fingernails

INTRODUCTION

Redness of the nail plate-erythronychia-is a common condition involving one or multiple digits. It may affect the entire nail or present as longitudinal red bands that extend from the proximal nail fold to the distal tip of the nail plate. Rarely, red bands may traverse the nail bed horizontally. Although erythronychia is often idiopathic, it has also been associated with amyloidosis, Darier's disease, lichen planus, and various other cutaneous conditions. We describe the clinical features of a 64-year-old Caucasian man who presented with transverse and longitudinal erythronychia affecting his fingernails. In addition, we review the classification of erythronychia and summarize the acute and chronic conditions that have been associated with this clinical finding.

METHODS

The features of a man with polydactylous transverse and longitudinal erythronychia are presented. In addition, PubMed was used to search the following terms: erythronychia, longitudinal erythronychia, red lunulae, and subungual. All papers were reviewed, and relevant articles, along with their references, were evaluated. Informed consent was obtained from the patient for being included in the study.

RESULTS

A 64-year-old Caucasian man with a past medical history significant for testicular cancer and pulmonary embolism presented with multiple horizontal pink-red bands affecting his fingernails. The discoloration was most prominent in the region distal to the lunula. In addition, the nails of the fifth digit of his left hand and third digit of his right hand featured longitudinal red bands extending from the distal curvature of the lunula to the free edge of the nail plate. A diagnosis of polydactylous longitudinal and transverse erythronychia, based on the clinical presentation, was established. Our patient's red bands were asymptomatic and he was not concerned about the cosmetic appearance of his nails; therefore, no additional investigation or treatment was required.

CONCLUSION

Polydactylous transverse erythronychia is a rare condition characterized by the development of horizontal red bands affecting the fingernails or toe nails. It has only been previously described in a man with multiple system atrophy. In our patient, both transverse and longitudinal red bands were present simultaneously. Therefore, it is possible that horizontal erythronychia is an early clinical manifestation of longitudinal erythronychia.

Acral Lentiginous Melanoma

Acral lentiginous melanoma (ALM) is a rare subtype of melanoma mainly arising on the palms, soles, and nail beds. ALM is the most common subtype of melanoma found in patients of Asian or African descent and tends to more advanced at presentation due to delays in diagnosis. Surgical treatment is difficult owing to the complexity and functional importance of the hands and feet and reconstruction after resection is usually needed. The prognosis for patients with ALM depends on stage of disease and tends to be worse than with other subtypes of melanoma. Newer treatment modalities such as immunotherapies and targeted agents are being tested in patients with advanced ALM with some promising preliminary results.

Glomus tumour

Glomus tumours are rare tumours accounting for only 1-5% of soft tissue tumours of the hand. They are described classically in the subungual region. We present the case of a 32-year-old woman with a late diagnosis of a glomus tumour that had caused her excruciating pain. Clinical examination was positive for Hildreth's sign and the Love test. Magnetic resonance imaging delineated the tumour, which was excised and confirmed histologically. This case highlights the continued delay in diagnosis of glomus tumours as well as the use of imaging in diagnosis and planning of surgery.

Subungual osteochondroma: Nail sparing excision

Subungual osteochondroma is a relatively uncommon benign bone tumor affecting mostly children and young adults, and is a major source of pain and nail deformity. Treatment consists of marginal excision and meticulous wound closure. In this report, we present three cases of subungual osteochondroma arising from the dorsal aspect of distal phalanx of the great toe, which were managed by marginal excision with preservation of nail apparatus under digital block anesthesia with the use of a ring tourniquet. We emphasize on the use of ring tourniquet made by glove's finger and the technique of preserving the nail apparatus to prevent nail deformity. At final follow-up, there is no evidence of recurrence or nail deformity with good functional and cosmetic result.

A rare case of multiple subungual glomus tumours in a neurofibromatosis type 1 patient

Glomus tumours are uncommon lesions of the digit. They tend to be solitary. Only a small number of multifocal cases have been published, most of which are linked to an underlying genetic disorder. Here we report an unusual case of multifocal glomus tumours in the same hand in a patient suffering from neurofibromatosis type 1.