Malignant melanoma developing from an intradermal nevus

SPECT/CT-Guided Surgical Removal of a Positive External Iliac Sentinel Node in Primary Umbilical Melanoma: Report of a Case, and Up-to-Date Review of the Literature

Primary umbilical melanoma is rare tumor, representing about 5% of all umbilical malignancies.The lymphatic drainage from the tumor is challenging and can be to inguinal, axillary and retroperitoneal nodes. Dynamic and static lymphoscintigraphy with single-photon emission tomography/computed tomography (SPECT/CT) and sentinel lymph node biopsy (SLNB) is a widely validated technique in patients with clinically localized melanoma to search for and quantify nodal spread of cutaneous melanoma. Moreover, it offers the surgeon the preoperative information about the number and location of the sentinel lymph nodes (SLNs), which makes SLNB easier and quicker. This is the first report of an ulcerated thick melanoma of the umbilicus metastasizing only to an external iliac lymph-node without involvement of superficial inguinal SLNs. The preoperative high-resolution ultrasound (HR-US) examination of the regional lymph node field had been normal. This case-report shows how addition of SPECT/CT to planar imaging in a patient with clinically localized umbilical melanoma can help avoid incomplete SLNB when a deep SLN is not removed. A literature review of umbilical melanoma is also provided.

Primary Cutaneous Umbilical Melanoma: The Michigan Experience

BACKGROUND

Primary cutaneous umbilical melanoma is rare. Thorough information regarding its characteristics and treatment, including use of sentinel lymph node biopsy (SLNB) staging, is difficult to obtain. The unique anatomy of the umbilicus adds to the complexity of diagnosing and treating melanoma at this site.

OBJECTIVE

To improve understanding of diagnosis and treatment of primary cutaneous umbilical melanoma through presenting 7 new cases and reviewing 39 cases in the literature.

MATERIALS AND METHODS

The University of Michigan melanoma database query and review of the literature regarding reported cases of primary umbilical melanoma.

RESULTS

In 7 new and 39 previously reported cases of primary cutaneous umbilical melanoma, we describe signs and symptoms, histopathologic features, differential diagnosis, relevant anatomical considerations, and definitive treatment including SLNB when applicable.

CONCLUSION

Our series, combined with a thorough literature review and compilation of findings, provides a better understanding and appreciation of melanoma in the unique anatomical site of the umbilicus, with a reminder to carefully examine the umbilicus during a full skin examination in patients at risk of melanoma. Primary umbilical melanoma presents and can be appropriately treated similarly to cutaneous melanoma in other sites, with attention to relevant anatomy.

Dermatoscopy of a primary dermal melanoma

This is a case report of a primary dermal melanoma and its dermatoscopic findings. A 50-year-old man in 2002 presented on the right anterior aspect of the thorax a 1.5-cm-diameter lesion with a rough surface and multiple papules of "vascular-like" appearance. It lacked the usual dermatoscopic findings, such as atypical pigmented network and radial streaks, related to the infiltration of malignant melanoma cells into the epidermis. Papillomatous projections with light brown and dark brown blotchy areas were seen under dermatoscopy, due to dermal melanin reflection from macrophages and neoplastic melanocytic cells near the junctional area. Other areas of papillomatous projections had a light brown-pink color surrounded by a thin whitish septum caused by the reflection of dermal vessels.

An intradermal nevus of the external auditory meatus

We herein describe a rare case of an intradermal nevus arising in the external auditory meatus. A 36-year-old woman presented with progressive hearing loss on the right ear, and otomicroscopic examination revealed the presence of a large, violaceous, dome-shaped, papillomatous lesion originating from the posterior wall of the external canal of the right ear. Upon excisional biopsy, the tumor was diagnosed as an intradermal nevus. Thus, this is a unique case of intradermal nevus obstructing the external ear canal with the patient presenting with progressive hearing loss. The possibility of a benign nevomelanocytic nevus should not be underestimated when evaluating a lesion obstructing the ear canal, and all melanocytic nevi should be excised instead of biopsied to rule out melanoma.

Problems in the interpretation of apparent "radial growth phase" malignant melanomas that metastasize

BACKGROUND

The delineation of radial and vertical growth phases in primary cutaneous malignant melanomas has contributed to our understanding of melanoma progression and has enhanced the ability of pathologists to provide clinicians with meaningful prognostic information. Vertical growth phase (VGP) lesions have the potential to metastasize, but radial growth phase (RGP) melanomas are believed to lack competence for metastasis.

METHODS

We have identified three cases in which metastasis occurred in association with lesions initially interpreted as RGP melanomas. To determine whether these cases truly represented exceptional metastasizing RGP melanomas or VGP lesions incorrectly identified as RGP lesions, careful microscopic re-review of these cases was performed.

RESULTS

In one case, additional microscopic sectioning revealed a focus of vertical growth that was not evident on the original sections. In the other two cases, only radial growth was found. In one of these cases there was melanoma in situ with regressive changes, but no evidence for invasive melanoma. In the other, a RGP lesion was associated with an adjacent compound nevus with periadnexal involvement.

CONCLUSIONS

These cases suggest that, while true RGP melanomas have an excellent prognosis, caution must be exercised in defining a lesion as having no metastatic potential when multiple sections of the primary lesion are unavailable, when the lesion is accompanied by regressive changes, or when there is an associated melanocytic nevus. It is possible that strictly defined RGP melanomas may metastasize in very rare cases. Our observations also suggest that metastatic potential is a function of numerous factors, and may not be evaluable on morphological grounds alone.