A melanocytic lesion combined with new-onset headaches is suggestive of malignant melanoma with CNS metastasis. Melanoma is a cancer of melanocytes, which are derived from neural crest cells.
Neural crest cells give rise to the peripheral nervous system as well as other nearby non-neural structures. Other than melanocytes, neural crest cells give rise to: autonomic nervous system, dorsal root/autonomic/cranial ganglia, cranial nerves, celiac ganglion, adrenal medulla chromaffin cells, enterochromaffin cells, parafolicular cells of the thyroid, Schwann cells, pia mater, arachnoid mater, skull bones, odontoblasts, laryngeal cartilage, and the aorticopulmonary septum.
Goldstein et al. discuss the diagnosis and management of malignant melanoma. A changing or atypical mole as well as multiple nevi greatly increase a patient's chances of developing melanoma. If this diagnosis is suspected, an excisional biopsy is necessary to stage the histologic grade/thickness of the tumor in order to determine appropriate treatment.
Mort et al. discuss the origin of melanocytes from the neural crest. The original A-P location of where the neural crest cells separate from the neural tube determines their ultimate function and cell type. The 5 location groups include cranial, vagal, sacral, trunk, and cardiac. The neural crest cells that derive from the trunk region of the neural tube give rise to melanocytes.
Illustration A shows the embryology of the formation of the neural tube and associated neural crest cells. Illustration B summarizes the derivatives of the neural crest cells; melanocytes are represented as 'pigment cells' in this depiction.
Answer 1: Ectoderm gives rise to the anterior pituitary, lens of the eye, skin, hair, nails, glands (mammary, sweat, salivary), as well as epithelial linings of the nose, external auditory meatus, mouth, and lower anal canal.
Answer 2: Neuroectoderm develops into the central nervous system, including all neurons in the brain and spinal cord, as well as retinal tissue, neurohypophysis, oligodendrocytes, astrocytes, ependymal cells, and the pineal gland.
Answer 3: Mesoderm gives rise to the muscle, dermis and subcutaneous skin layers, bone, cartilage, connective tissue, dura mater, peritoneum, spleen, cardiovascular structures, lymphatics, blood components, urogenital structures, kidneys, and adrenal cortex.
Answer 5: Endoderm develops into the liver, parathyroid, thyroid follicular cells, thymus, pancreas, and the epithelial linings of respiratory tract, urinary tract, GI tract, biliary system, lower 2/3 of the vagina, and the middle ear.
Goldstein BG, Goldstein AO. Diagnosis and management of malignant melanoma. Am Fam Physician. 2001 Apr 1;63(7):1359-68, 1374.
PMID:11310650 (Link to Abstract)
Mort RL, Jackson IJ, Patton EE. The melanocyte lineage in development and disease. Development. 2015 Feb 15;142(4):620-632.
PMID:25670789 (Link to Abstract)