Multiple Familial Trichoepithelioma with an Adjacent Basal Cell Carcinoma, Transformation or Collision - A Case Report and Review of Literature

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

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 established-whether 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.

Clear Cell Hidradenoma-Basal Cell Carcinoma Collision

ABSTRACT

A 91-year-old man presented with a tumor on the left temporal area, clinically suspicious of basal cell carcinoma. The histopathologic study showed a central solid-cystic tumor composed by 3 different types of cells (clear or finely granular cells, polygonal cells, and squamoid cells). It had a sclerotic stroma. At the periphery, another tumor composed by smaller interconnected nests was evident. Some nests were separated from the stroma by clefts. The stroma of this second tumor was highly cellular. There was a sharp delimitation between both tumors, with no transitional area. Immunochemistry demonstrated they are different tumor. A diagnosis of clear cell hidradenoma-basal cell carcinoma collision was performed. To the best of our knowledge, this is the first description of this challenging association.

Trichoepithelioma Misdiagnosed as Basal Cell Carcinoma

Trichoepithelioma is a benign tumor which can be easily confused with basal cell carcinoma. Since both tumors are histologically similar, it is important to distinguish them correctly as the courses for treatment are very different. Basal cell carcinoma is malignant; therefore, it requires total surgical excision, including a wide healthy margin. In contrast, trichoepithelioma requires only simple excision. A study involving a 69-year-old woman with a simple mass on the nasal tip was described in this study. On examination, a single skin-colored, round protruding mass (approximately 0.5 × 0.5 cm) was observed. Simple excision was performed and basal cell carcinoma was diagnosed at the initial biopsy. However, clinically, we considered it to be a benign tumor; therefore, we sought a histologic reconfirmation. Consequently, trichoepithelioma was diagnosed on histopathologic examination. When a small, round protruding simple mass is histologically diagnosed to be a basal cell carcinoma, it is important to suspect trichoepithelioma and seek histologic reconfirmation.

A rare development of basal cell carcinoma on trichoepithelioma in a chemical burn scar tissue: A case report

RATIONALE

Trichoepithelioma (TE) is a rare benign skin tumor that originates from the hair follicle epithelium. Although skin lesions arising from scar tissues are mostly malignant, the development of a benign tumor such as TE is a rare event.

PATIENT CONCERNS

A 28-year-old male patient who had a scar on the left cheek which arose 10 years ago because of a chemical burn visited our hospital. Scar revision was performed under local anesthesia.

DIAGNOSIS

Histological examination identified the specimen as a TE with malignant foci suspicious of basal cell carcinoma (BCC) at the lateral margin of the specimen.

INTERVENTIONS

A second stage operation was planned to excise the BCC with a 4 mm margin of the normal skin around the previous lesion.

OUTCOMES

No complication or recurrence was noted during the 1-year follow-up period after surgery, and the appearance of the scar improved.

LESSONS

The correct differential diagnosis between TE and BCC is very important. So follow up at regular intervals is recommended for evaluation of recurrence or transformation into BCC in patients with tumors arising from chemical burn scars. And the concomitant development of TE and BCC should also be considered from a chemical burn scar.

Trichoadenoma of Nikolowski- A Rare Tumour with Unusual Presentation Over Vulva

Trichoadenoma is a rare benign, slowly growing, cutaneous tumour of the hair follicle first described by Nikolowski in 1958. It presents as a non-specific nodule over the face or buttocks. However, unusual sites such as the neck, upper arm, thigh, shoulder, and shaft of the penis may also be affected. The tumour is less mature than a trichofolliculoma and is more differentiated than a trichoepithelioma with a differentiation towards the infundibular portion of the pilosebaceous canal. Histologically, it consists of numerous infundibulocystic structures present throughout the dermis, few of which are lined by eosinophilic epidermal cells with attempted glandular formation and contain laminated keratin, without evidence of hair follicle formation. We report a case of trichoadenoma over the vulva of 25-year-old female showing typical histological features.

Basal Cell Carcinoma Developing from Trichoepithelioma: Review of Three Cases

Trichoepitheliomas (TE) are benign tumours but occasionally can undergo transformation to malignant neoplasms more commonly as Basal Cell Carcinoma (BCC). The correct diagnosis between these tumours is very important because basal cell carcinoma is locally aggressive neoplasm and requires total surgical excision with wide healthy margins while trichoepithelioma needs simple excision. We describe three patients who developed basal cell carcinoma with facial trichoepitheliomas. The only clinical feature that distinguished the carcinomas from the trichoepitheliomas was their larger size, in all three patients, one patient with recurrent, hyper pigmented swelling with surface ulceration and in another patient there are multiple trichoepitheliomas, and other family members are also affected. The history, clinical features and histopathological findings were suggestive of the evolution of basal cell carcinoma directly from trichoepithelioma in our first two cases, but in the third case TE and BCC were separate lesions on face and we are uncertain about whether the BCC developed independently or by transformation from a trichoepithelioma. Based on our clinicopathological observations in the three patients and reports in the recent literature, BCC with follicular differentiation and trichoepithelioma are considered to be highly related.