Lack of distinct molecular profile of Primary Dermal Melanoma

Primary Dermal Melanoma

Primary dermal melanoma (PDM) is a rare subtype of melanoma with an estimated incidence of less than 1%. PDM presents entirely in the dermis or subcutis and histopathologically mimics cutaneous metastases of melanoma due to its lack of connection to the overlying epidermis. A thorough history and examination, including imaging evaluation for metastatic disease, will reveal no prior history or concurrent lesion of primary cutaneous or metastatic melanoma. Despite its histopathologic similarities to melanoma metastasis, PDM is associated with an unexpectedly favorable prognosis. This review discusses the clinical and histopathologic features of PDM as a distinct subtype of melanoma, as well as the current approach to clinical staging and management.

A nodule on the upper back of an older woman

We present the case of a solitary nodule on an older patient's upper back. This case highlights the diagnostic challenges and important distinguishing features for prompt identification and management.

Metastatic melanoma and rare melanoma variants: a review

The histopathological diagnosis of melanoma is fraught with potential pitfalls. In the setting of cutaneous metastatic melanoma, it is important to recognise the various histological patterns that can be encountered from the more common to the rare, including epidermotropic, folliculotropic, naevoid, and blue naevus-like. In addition, melanoma is notorious for phenotypic plasticity. Thus, there are many different subtypes and cytomorphological variations that can be difficult to recognise as melanoma, particularly in the recurrent or metastatic setting. Select melanoma variants including primary dermal, clear cell, plasmacytoid, signet ring cell, small cell, myxoid, rhabdoid, and dedifferentiated melanoma will be discussed, in addition to composite melanocytic neoplasms. This review is intended to remind the practitioner of key concepts of metastatic disease and select rare melanoma variants, while providing practical guidelines for accurate diagnosis.

Primary Dermal Melanoma: A Case Report

ABSTRACT

Primary dermal melanoma (PDM) is defined as a primary melanoma tumor confined to the dermis, subcutis, or both, without epidermal involvement. The significant overlap of histopathological features in PDM and cutaneous metastatic melanoma makes diagnostic accuracy of PDM challenging. We present a case of a 48-year-old man with a nontender 1.5 × 1.5 cm subcutaneous nodule on the left leg, which had been present for years. Biopsy revealed a dermal tumor with melanocytic differentiation noted to be positive for SOX-10. Additional pathology findings included a high Ki-67 proliferation index and a loss of p16 expression. Pathology reports were consistent with primary tumor stage 4a, and the patient was referred to surgical oncology where examination and workup demonstrated no evidence of the residual lesion representing a metastasis from a primary site. As PDM is histologically indistinguishable from melanoma metastasis to the skin, clues including a history of an evolving subepidermal nodule and exclusion of previous or concurrent melanomas can assist in its accurate diagnosis. Currently, a consensus on the criteria, staging, and management of PDM does not exist. Poorly defined diagnostic criteria and general lack of awareness of PDM result in high rates of incorrect and late-stage diagnoses. This case report highlights the importance of physician familiarity with PDM to ensure accurate recognition, evidence-based management, and improved patient outcomes.

Primary Dermal Melanoma: A Rare Clinicopathological Variant Mimicking Metastatic Melanoma

Primary dermal melanoma (PDM) is a rare distinct variant of cutaneous melanoma, predominantly occurring on the extremities of young or middle-aged adults. In comparison to conventional melanoma, PDM is characterized by unexpectedly prolonged survival and long-term survival. Thus, correct identification of this variant is crucial to avoid potential misdiagnosis and establish correct treatment and follow-up. In addition, no consensus and specific guidelines exist on the management of this peculiar subtype of cutaneous melanoma.