DISCUSSION:


Pilomatricoma
Pilomatricoma is an uncommon, harmless, hair follicle tumour derived from hair matrix cells. It is also spelled ‘pilomatrixoma’, and sometimes known as ‘calcifying epithelioma of Malherbe’.
Pilomatricoma is most often diagnosed in young children but may also affect adults. Single skin-coloured or purplish lesions arise on the head and neck, but they may occur on any site. They are characterised by calcification within the lesion, which makes it feel hard and bony, and often results in an angulated shape (the ‘tent’ sign).
The cause of pilomatricoma is unknown. However, recently some genetic changes have been found in the affected hair cells (an overactive proto-oncogene called BCL-2 suggests the normal process of cell death is suppressed and mutations in CTNNB1 suggest loss of regulation of a protein complex called beta-catenin/LEF).


Complications of pilomatricoma
Complications of pilomatricoma are rare. However, occasionally they grow to giant size (several centimetres in diameter), and pilomatrix carcinoma (cancer) has been very rarely reported.
A few cases have been reported of multiple pilomatricomas in association with the rare neurological condition myotonic dystrophy. Individual cases have also been reported of pilomatricomas arising in patients with a variety of other genetic disorders. The vast majority are not associated with any other abnormality.



How is the diagnosis of pilomatricoma made?
If the nature of the skin lesions is uncertain, ultrasound scan may be recommended. The scan of pilomatricoma is described as a doughnut within the dermis (mid layer of the skin) with a tail (the tail denotes calcification). Alternatively, the calcification may be detected by X-ray.
Quite often, a small biopsy (when a tiny piece of skin is removed under local anaesthetic) will help to establish the cause of the lesion. Alternatively the whole lesion can be removed providing both diagnosis and treatment. The histology of pilomatricoma is striking. It may show a sharply demarcated tumour surrounded by a fibrous capsule or a poorly demarcated tumour without capsule. There are darkly stained ‘basophilic’ cells and ‘shadow’ cells with missing nuclei. Calcium deposits are found in most lesions.



What is the treatment for pilomatricoma?
It is generally recommended that the pilomatricoma be cut out (excised). They do not disappear by themselves, and if incompletely removed, they may recur.
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毛母質瘤又稱鈣化上皮瘤,是源自向毛母質細胞分化的原始上皮胚芽細胞的一種良性腫瘤。多見於女性,通常在兒童期或青年期發病,本病可惡變為毛母質癌,惡變率約為2.6%。發病高峰期女性為5~15歲,男性為5歲。本病不遺傳,但少數有家族史。
病因
多見於頭皮和面頸部,軀干、肢體及其他部位也可發生。
腫物位於皮內或皮下,通常單發,偶或多發。罕見情況下,腫瘤呈突出表面界限清楚的暗紅色結節,直徑一般在0.5~3cm大,最大可達7cm,偶爾更大,基底可推動。常見皮損表現為堅實的、深在結節,偶呈囊性。表面皮膚外觀正常,偶因位置較深而呈藍紅色,或呈紅色、淡藍色。
輔助檢查
主要依靠組織病理學檢查。組織病理顯示:腫瘤邊界清,周圍往往有結締組織包膜,常位於真皮下部並擴展至皮下組織,為不規則形上皮細胞島,嵌於細胞較多的間質中,上皮細胞島由嗜鹼性細胞或無核的嗜酸性細胞組成,常伴有鈣質沉著。通常腫瘤由兩型細胞即嗜鹼性粒細胞和影細胞構成。嗜鹼性粒細胞有圓或長形深嗜鹼性胞核,胞質不多,致胞核彼此密集,其邊界常不清楚,因而胞核似嵌於合漿團塊內一樣。嗜鹼性粒細胞排列在腫瘤的一側或周邊。這些細胞在某些區域可驟變為影子細胞,后者細胞邊界清楚,中央為不著色區,恰如胞核消失的影子。新發生的腫瘤內有很多嗜鹼性粒細胞區,腫瘤增長時,嗜鹼性粒細胞減少,在長期存在的腫瘤中殘留少數或無嗜鹼性粒細胞。也可出現骨化,黑色素沉積和伴發巨細胞的異物反應。
診斷
根據臨床表現和組織病理學表現確診。
需要和鱗狀細胞癌、外毛根鞘囊腫、毛囊瘤、實體型基底細胞上皮瘤等相鑒別。
治療
手術切除活檢為最好的治療方法。亦可通過小切口銳匙刮術,刮除囊內容。手術完整切除很少復發。少數可惡變為毛母質癌。早期手術切除,預后較好。






化驗報告:毛母質瘤/鈣化上皮瘤

主診醫生:鍾經略醫生

監督及指導機構: 英國威爾斯大學/卡的夫大學臨床皮膚專科部門。

皮膚科醫生常見皮膚疾病 – 毛母質瘤, 鈣化上皮瘤

​  ​中環鍾經略醫生【皮膚學碩士 x 美容醫學碩士】(課程研究)

化驗報告:毛母質瘤/鈣化上皮瘤

此毛母質瘤/鈣化上皮瘤的皮膚科醫學照片由鍾經略醫生於診所拍攝,版權所有。