Multiple Spitz nevi: A clinicopathologic study of 9 patients

GOPC-ROS1 mosaicism in agminated Spitz naevi: report of two cases

Spitz tumors are genetically associated with activating HRAS point mutations or fusions of either ALK, ROS1, NTRK1, NTRK3, RET, MET, MERTK, LCK, BRAF, MAP3K8, or MAP3K3. All these driver gene alterations are mutually exclusive. We report two cases of agminated Spitz naevi with a GOPC-ROS1 fusion. Both cases occurred on the lower limb of young adults. Since adolescence, pigmented or pink-colored papules have been periodically arising in a limited area of skin. In one case, an ill-defined hyperpigmented macule known since childhood was present in the background. Morphologically, at least five lesions were analyzed from each patient. In one case, all were predominantly junctional pigmented Spitz naevi, and in the other case, all were compound unpigmented Spitz naevi. No atypical features were present. RNA-sequencing revealed a GOPC-ROS1 gene translocation in both cases. Split signals of ROS1 gene in fluorescence in situ hybridization were observed not only in the nests of spitzoid melanocytes but also in the bland basal melanocytes surrounding the proliferations. These findings suggest the presence of a GOPC-ROS1 mosaicism in melanocytes with further emergence of agminated Spitz naevi potentially triggered by other genetic alterations. This expands the spectrum of genetic anomalies described in agminated Spitz naevi and our understanding of the mechanisms involved in their emergence.

[Laser treatment of pigmentation disorders]

Pigmentation disorders are among the most common cutaneous changes and occur in up to 60% of all people. They can be genetic or acquired, functionally or cosmetically disturbing, or the expression of a medical disorder. The best treatment options for hyperpigmentation are usually lasers and intense pulsed light (IPL). However, they can also worsen some conditions and are occasionally associated with side effects. A correct diagnosis is therefore essential, taking into account the skin type, the type of pigmentation and how deep the pigmentation is located in the skin. The most common indications for which laser treatment is recommended include genetically predisposed nevi (Becker, Ota, Hora, Ito, acquired bilateral nevus of Ota-like macules [ABNOM]), pigmentation (e.g., lentigines, postinflammatory hyperpigmentation, ephelides, café au lait, nevus spilus, linear and whorled hypermelanosis [LWNH]), nevus cell nevi, exogenous pigments, tattoos and cosmetic pigments.

Novel three-way complex rearrangement of TRPM1-PUM1-LCK in a case of agminated Spitz nevi arising in a giant congenital hyperpigmented macule

The genetic anomalies associated with the agminated variant of Spitz nevus have so far been limited to HRAS G13R mutations, especially when arising within a nevus spilus. A previous report exposed the case of a man with a giant pigmented macule involving his upper right limb and trunk. Since childhood, Spitz nevi have been periodically arising, within the pigmented area. The histopathology of several lesions displayed the usual criteria of junctional, compound, or intradermal Spitz nevi with a diversity of cytomorphological and architectural features. Some lesions spontaneously regressed. Genetic studies confirmed in three lesions an identical translocation involving TRPM1, PUM1, and LCK. No mutations in HRAS, NRAS, BRAF, or other known fusion genes linked to Spitz nevus were detected. LCK break-apart fluorescence in situ hybridization confirmed the rearrangement was present not only in the melanocytic proliferation but also in the surrounding non-spitzoid melanocytes. This report expands the list of genetic alterations involved both in giant congenital macules and in agminated Spitz nevi, and also extends the concept of mosaicism in melanocytes to gene translocations.

Multiple Spitz nevi after allogeneic hematopoietic stem cell transplantation

Spitz nevus commonly appears as a solitary lesion. A 12-year-old male patient presented with a 6-month history of several pigmented lesions on his trunk and lower extremities. He had undergone chemoradiotherapy and unrelated umbilical cord blood transplantation against recurring acute lymphoblastic leukemia for 6 years. After that, several pigmented lesions abruptly developed on his trunk and lower extremities, and the number of those increased significantly. Pathologically, the diagnosis of multiple Spitz nevi was made. In a clinical correlation, we diagnosed multiple Spitz nevi resulting from such an immunocompromised condition. This is the first description of clinical, dermoscopic, and histopathologic features of multiple Spitz nevi in the hematopoietic cell transplantation (HSCT) recipient child.

Eruptive disseminated Spitz naevus (EDSN) in a young girl of Indian origin

Eruptive disseminated Spitz naevus (EDSN) is a rare entity and has never been documented in a South-east Asian individual (of Indian origin) previously. We report an adolescent with this condition which, to our knowledge, has only been previously reported a few times.