Black and Brown Oro-facial Mucocutaneous Neoplasms

HRAS-mutated primary thyroid malignant melanoma or medullary thyroid carcinoma with melanocytic dedifferentiation? A singular case with an ontogeny-phylogeny quandary

Melanotic pigment in the thyroid is practically synonymous with chronic minocycline therapy and rare cases of melanotic medullary thyroid carcinoma. However, primary melanoma of the thyroid has not been reported yet. We report a rare case of a 25-year-old male with a locally aggressive thyroid mass and distant metastases at presentation. Radiologically, a 8.3×7.6-cm nodule was identified in the right thyroid lobe. Fine-needle aspiration cytology (FNAC) showed discohesive atypical plasmacytoid cells with prominent nucleoli and no cytoplasmic pigmentation. Serum calcitonin levels were normal. A trucut biopsy showed a malignant tumor with a similar cytomorphology, including marked nuclear pleomorphism. In addition, intracytoplasmic melanin was seen in <1% of cells. Tumor cells were immunonegative for AE1/AE3, TTF1, synaptophysin, and chromogranin while positive for SOX10, S100P, HMB45, and Melan A, confirming the diagnosis of malignant melanoma, without any detectable MTC component in the biopsy. An HRAS G13R mutation was detected on NGS, which, intriguingly, is a known mutation in MTC, and exceedingly rare in melanocytic lesions. No other clinically or radiologically apparent primary lesion was identified elsewhere in the patient. The unusual histology and hitherto unreported molecular findings make this case of primary thyroid melanocytic neoplasm worth reporting. Abstruse origin of melanoma cells in the thyroid gland with molecular signature suggestive of MTC in our case raises a nomenclature and management conundrum, prompting us to revisit the "ontogeny recapitulates phylogeny" theory.

Congenital Melanotic Macule of the Tongue: Report of Two Cases and Literature Review

BACKGROUND

Congenital melanotic macule of the tongue (CMMT) has been described as a distinct entity, despite its unknown etiology. However, the diagnosis and management of affected newborns may challenge clinicians and pediatric dentists.

METHODS

We document here the clinicopathological findings of two additional cases of CMMT. A literature review of CMMT reports identified across PubMed, Web of Science, Embase, and Scopus was also conducted.

RESULTS

The patients, 2- and 4 month-old Venezuelan boys, respectively, presented at birth with a single or multiple dark-brown-pigmented macule exclusively on the dorsum of the tongue. Histopathological features revealed increased melanin pigmentation in the basal epithelial layer with overlying hyperkeratosis and pigment-laden subepithelial macrophages with normal morphological appearance. Nine studies comprising 17 cases of CMMT have been described hitherto. Most cases were from the USA and France (n = 6 each). Twelve (70.6%) patients were males, eight (50%) were white, and median age was 2.7 months. CMMT presented as brownish to black, solitary or multiple pigmentations located in the right or left region of the dorsum of the tongue, ranging in size from 3.0 to 30.0 mm.

CONCLUSION

An important feature for the diagnosis of CMMT is the information about the manifestation at birth and consequent proportional growth. This report intends to draw the attention of pediatricians and dentists to this apparently underdiagnosed condition for decision-making and management of affected newborns.

Intraoral atypical lentiginous melanocytic lesion in a pediatric patient

We present a rare case of intraoral atypical lentiginous melanocytic lesion affecting a pediatric patient, in which the diagnosis of lentiginous junctional melanocytic nevus with cytologic atypia was favored. The main differential diagnosis is lentiginous melanoma, which is a slowly progressing lesion, affecting mainly older adults, and microscopically presenting lentiginous growth pattern of moderately atypical melanocytes, with focal nesting and pagetoid spread. It is strongly recommended that melanocytic lesions showing features of atypical lentiginous growth pattern should be treated with wide excision; however, the impact of these guidelines on pediatric patients needs to be better defined with the report of further cases.