<p>Multiple Skin Neoplasms at One Site (MUSK IN A NEST): A Comprehensive Review of Basal Cell Carcinoma and Benign or Malignant “Collision” Tumors at the Same Cutaneous Location</p>

Abstract

Multiple skin neoplasms at one site (MUSK IN A NEST), initially referred to as a collision tumor, describes the occurrence of two or more benign or malignant neoplasms that are adjacent or intermingled at the same cutaneous site. A mononeoplastic cutaneous tumor refers to a single tumor at any cutaneous site. Two, three, four, five, and six tumors at the same site are described as dineoplastic, trineoplastic, tetraneoplastic, pentaneoplastic, and hexaneoplastic cutaneous tumors, respectively; the prefixes are based on the numerical multiplier used by the International Union of Pure and Applied Chemistry (IUPAC). MUSK IN A NEST can be classified based upon their mechanism of pathogenesis-either being composed of mixed clones of cells (clonalium, which has three subtypes: collision, colonization, and combination) or the same clone of cells that has undergone clonal evolution (clonalidem, which has one subtype: biphenotypic). Basal cell carcinoma (BCC)-associated MUSK IN A NEST can be observed with either benign tumors, malignant tumors, or both. Nevi and seborrheic keratoses are the most common benign tumors associated with BCC; melanoma in situ and invasive melanoma are the most commonly reported malignant tumors associated with BCC. The definitive etiology of BCC-associated MUSK IN A NEST remains to be establishedwhether the development of the BCC at that site occurs as a direct or indirect consequence of the coexisting neoplasm or whether the occurrence of the BCC and the other neoplasm is merely the result of a coincidental juxtaposition of the tumors.

Combined Mohs Micrographic Surgery in a Collision Tumor

“…Collision skin tumors are a common finding in both benign and malignant tumors. However, the collision of basal cell carcinoma and melanoma is infrequent and found in 1.4 per 100,000 basal cell carcinomas [6].…”

Multiple skin neoplasms at one site (MUSK IN A NEST): collision tumor consisting of epidermal (macular seborrheic keratosis) and dermal (lichen amyloidosis) components

“…MUSK IN A NEST, initially referred to as a collision tumor, can consist of two or more malignant neoplasms, one or more malignant and benign disorders, or two or more benign conditions [4]. Seborrheic keratosis and cutaneous amyloidosis have both been a component of a MUSK IN A NEST [4,6].…”

“…Cutaneous collision tumors, which has recently been designated as multiple skin neoplasms at one site (MUSK IN A NEST), consist of two or more neoplasms concurrently located at the same cutaneous location [4]. Seborrheic keratosis and amyloidosis have both been components of MUSK IN A NEST; although it is likely that a seborrheic keratosis and lichen amyloidosis have previously occurred as a collision tumor, to the best of our knowledge, a report of this phenomenon has not been published.…”

Topical treatment of skin rashes in monkeypox owing to a jelly containing Mediterranean seasosings in tragacanth and arrowroot

“…Basal cell carcinoma (BCC) is the most common human cutaneous malignant epithelial neoplasm [1][2][3]. BCC occurs in sporadic (non-syndromic) and syndromic (hereditary) forms.…”