Solitary Cutaneous Myxoma in a Child: Rare Entity

Solitary cutaneous myxoma (SCM), sometimes referred to as superficial angiomyxoma because of its vascular component, is relatively rare. They usually occur as an asymptomatic nodule with slow growth on the head, neck, and trunk usually in adults [1, 2]. Rarely, they locate at the acral level [2]. SCM should be distinguished from the complex of myxomas (cardiac, cutaneous and breast), speckled pigmentation (cutaneous and mucocutaneous) and endocrine hyperactivity (Cushing's syndrome, sexual precocity and acromegaly) described by Carney et al., [3].


Introduction
Solitary cutaneous myxoma (SCM), sometimes referred to as superficial angiomyxoma because of its vascular component, is relatively rare. They usually occur as an asymptomatic nodule with slow growth on the head, neck, and trunk usually in adults [1,2]. Rarely, they locate at the acral level [2]. SCM should be distinguished from the complex of myxomas (cardiac, cutaneous and breast), speckled pigmentation (cutaneous and mucocutaneous) and endocrine hyperactivity (Cushing's syndrome, sexual precocity and acromegaly) described by Carney et al., [3].
We report a case of solitary cutaneous myxoma sitting on the scalp of a young child.

Observation
An 11-year-old child, with no notable pathological history, presented with swelling in the scalp for 3 years, with a very progressive increase in size. Dermatological examination showed the presence of a 1.5 cm nodule, pale pink in color, bilobed smooth surface, fixed in relation to the deep plane, painless and non-pruriginous. The diagnoses evoked were a keloid scar or a pilomatricoma. The histological study showed tumor proliferation in the superficial dermis made of fusiform stellate cells arranged on a loose and myxoid base with a fine vascularization. An immunohistochemical study made of PS100 came back negative. The diagnosis of benign cutaneous myxoma was retained. The child underwent surgical resection of the nodule, with a recoil of 10 months without recurrence.

Discussion
SCM has been described as a "hairy flesh colored nodule" or as a "soft, lobulated nodule" [1]. Over the years, only a few cases have been reported of cutaneous solitary or multiple cutaneous myxomas without systemic features [1,2]. Multiple cutaneous myxomas have generally been attributed to the Carney complex [4], NAME [5], or LAMB [6] syndromes. The cutaneous myxomas that accompany the Carney complex usually affect young patients, and are usually less than 1 cm in size. They are multiple and have a widespread distribution with a predilection for eyelids, ears and nipples. Usually, they are described as asymptomatic, sessile, subcutaneous papules or nodules with a non-ulcerated surface; rarely, they are rough and papillomatous. These cutaneous myxomas announce the presence of a potentially serious cardiac OPEN ACCESS https://scidoc.org/IJPA.php tumor, and after the excision, tend to the local recurrence, in spite of their benign nature. Solitary myxomas, without other manifestations of Carney Complex, are generally localized in the skeleton or cardiac muscle, less frequently in the intestines, the pelvis, subcutaneously [3], and very rarely in the skin. Dutz et al., [7] reported 15 myxomas from subcutaneous tissue in children, but not in the dermis. Other reports in the literature [8,9] describe small lesions classified as cutaneous focal mucinosis, which are not considered to be true myxomas. They are characterized by local accumulations of mucin in the dermis with spindle-shaped cells, but with less vascularization than myxomas [2].
Solitary cutaneous myxomas are located in the dermis or subcutaneous tissue. They are generally well-limited, without peripheral capsule when they are localized at the level of the dermis and sometimes encapsulated when they are located at the subcutaneous fat level. The stroma is very hypocellular, myxoid, and contains mucopolysaccharides. Within this stroma, fusiform and star-shaped cells with oval nuclei and poorly defined cytoplasm are present [10]. Other lesions include myxoid deposits such as myxoid neurofibroma, neurotheleomeoma and fibromyxoid tumor (ossifying and non-ossifying) which must be differentiated from cutaneous myxoma through histological examination with immunohistochemical study. We describe a case of solitary cutaneous myxoma on the scalp of an 11-year-old child with no other features of the Carney complex, no evidence of cardiac myxoma, and no family history of this autosomal dominant disorder. No evidence of local recurrence is noted 10

Conclusion
Although it is necessary for the clinician and the pathologist not to misunderstand the association between cutaneous myxoid tumors and cardiac myxomas given the seriousness of this table considered as a potentially fatal risk, we would like to emphasize the occurrence of sporadic cases of cutaneous myxomas as an entity in itself, and to distinguish it from other cutaneous myxoid neoplasms.