Mastocytosis, a type of mast cell disease, is a rare disorder affecting both children and adults caused by the accumulation of functionally defective mast cells (also called mastocytes) and CD34+ mast cell precursors.People affected by mastocytosis are susceptible to a variety of symptoms, including itching, hives, and anaphylactic shock, caused by the release of histamine and other pro-inflammatory substances from mast cells. Signs and symptoms
When mast cells undergo degranulation, the substances that are released can cause a number of symptoms that can vary over time and can range in intensity from mild to severe. Because mast cells play a role in allergic reactions, the symptoms of mastocytosis often are similar to the symptoms of an allergic reaction. They may include, but are not limited to
Fatigue
Skin lesions (urticaria pigmentosa), itching, and dermatographic urticaria (skin writing)
"Dariers Sign", a reaction to stroking or scratching of urticaria lesions. Abdominal discomfort
Nausea and vomiting
Diarrhea
Olfactive intolerance
Ear/nose/throat inflammation
Anaphylaxis (shock from allergic or immune causes)
Episodes of very low blood pressure (including shock) and faintness
Bone or muscle pain
Decreased bone density or increased bone density (osteoporosis or osteosclerosis)
Headache
Depression
Ocular discomfort
Increased stomach acid production causing peptic ulcers (increased stimulation of enterochromaffin cell and direct histamine stimulation on parietal cell)
Malabsorption (due to inactivation of pancreatic enzymes by increased acid)
HepatosplenomegalyThere are few qualitative studies about the effects of mastocytosis on daily life. However, a Danish study from 2018 describes the multidimensional impact of the disease on everyday life. Pathophysiology
Mast cells are located in connective tissue, including the skin, the linings of the stomach and intestine, and other sites.
Lentigo maligna melanoma is a melanoma that has evolved from a lentigo maligna,: 695  as seen as a lentigo maligna with melanoma cells invading below the boundaries of the epidermis. They are usually found on chronically sun damaged skin such as the face and the forearms of the elderly. Lentigo maligna is the non-invasive skin growth that some pathologists consider to be a melanoma-in-situ. A few pathologists do not consider lentigo maligna to be a melanoma at all, but a precursor to melanomas. Once a lentigo maligna becomes a lentigo maligna melanoma, it is treated as if it were an invasive melanoma. Presentation
An invasive tumor arising from a classical lentigo maligna. Usually a darkly pigmented raised papule or nodule, arising from a patch of irregularly pigmented flat brown to dark brown lesion of sun exposed skin of the face or arms in an elderly patient. Diagnosis
The first problem is difficulty. As lentigo malignas often present on severely sun damaged skin, it is frequently found amongst numerous pigmented lesions – thin seborrheic keratoses, lentigo senilis, lentigines. It is difficult to distinguish these lesions with the naked eye alone, and even with some difficulty using dermatoscopy. As the lentigo maligna is often very large, it often merges with, or encompasses other skin tumors – such as lentigines, melanocytic nevi, and seborrheic keratosis. The second difficulty   is the biopsy technique. Even though excisional biopsy (removing the entire lesion) is ideal, and advocated by pathologists, practical considerations may indicate that this should not be done.