Microcystic Adnexal Carcinoma

Abstract

Microcystic adnexal carcinoma (MAC) is a locally aggressive neoplasm that has recently been recognized as a clinicopathologic entity. Its histologic appearance includes both pilar and eccrine differentiation. We initially treated two patients with MAC of the cheek and of the nasolabial fold, respectively; by microscopically controlled excision because of the contiguous growth of the tumors. Despite the benign histologic appearance, there was deep and extensive infiltration of the subcutaneous tissue. Both patients responded favorably to initial treatment with microscopically controlled excision. In addition, immunoperoxidase staining for carcinoembryonic antigen supported the dual differentiation of this unusual neoplasm. We speculate that previous radiotherapy may be an important predisposing factor in the pathogenesis of MAC.

Microcystic Adnexal Carcinoma of the Scalp

“…Treatment has included local wide excision, radiation alone, 10 excision followed by radiation, 1 and Mohs surgery 6–8 . Of 15 patients reported by Cooper et al, 2 9 (60%) had one or more recurrences after initial surgical excision.…”

“…Two of the 6 patients (33%) reported by Goldstein et al 1 had recurrences after treatment. Three cases described in the literature were treated with Mohs surgery 6–8 with one case having a recurrence 2 years after treatment 7 . Of the remaining cases that were reviewed, there is insufficient data regarding recurrences.…”

“…Sweat gland differentiation has been a consistent feature of MAC based on light‐microscopic evidence of duct formation and evidence of CEA immunoperoxidase staining within these ducts 6 . However, pilar differentiation has also been suggested based on microscopic evidence of abortive hair follicle and keratin cyst formation 4 .…”

Microcystic Adnexal Carcinoma of the Scalp

“…Treatment has included local wide excision, radiation alone, 10 excision followed by radiation, 1 and Mohs surgery 6–8 . Of 15 patients reported by Cooper et al, 2 9 (60%) had one or more recurrences after initial surgical excision.…”

“…Two of the 6 patients (33%) reported by Goldstein et al 1 had recurrences after treatment. Three cases described in the literature were treated with Mohs surgery 6–8 with one case having a recurrence 2 years after treatment 7 . Of the remaining cases that were reviewed, there is insufficient data regarding recurrences.…”

“…Sweat gland differentiation has been a consistent feature of MAC based on light‐microscopic evidence of duct formation and evidence of CEA immunoperoxidase staining within these ducts 6 . However, pilar differentiation has also been suggested based on microscopic evidence of abortive hair follicle and keratin cyst formation 4 .…”

Microcystic Adnexal Carcinoma: A Case Showing Eccrine Duct Differentiation

“…In difficult cases, immu‐nostaining for CEA has enabled the pathologist to distinguish between similar histologic entities, such as syringoma and desmoplastic trichoepithelioma 14 . Previous investigators have demonstrated immunoreactivity for CEA in lesions of MAC 15 . Immunohistochemically, only the ductal structures manifest CEA; the pilar structures are predictably unreactive for this marker 11 …”

Syringoid Eccrine Carcinoma

“…Goldstein described “islands of basaloid keratinocytes often containing horn cysts and abortive follicles … embedded in a desmoplastic stroma.” 4 Another prominent pattern has been described as dilated cysts and branching tubular structures; tadpole‐shaped epithelial islands may also be present 5,14,15 . The ducts are usually filled with an eosinophilic material and are most frequently lined by two cell layers.…”

Microcystic Adnexal Carcinoma of the Scalp

“…Treatment has included local wide excision, radiation alone, 10 excision followed by radiation, 1 and Mohs surgery 6–8 . Of 15 patients reported by Cooper et al, 2 9 (60%) had one or more recurrences after initial surgical excision.…”

“…Two of the 6 patients (33%) reported by Goldstein et al 1 had recurrences after treatment. Three cases described in the literature were treated with Mohs surgery 6–8 with one case having a recurrence 2 years after treatment 7 . Of the remaining cases that were reviewed, there is insufficient data regarding recurrences.…”

“…Sweat gland differentiation has been a consistent feature of MAC based on light‐microscopic evidence of duct formation and evidence of CEA immunoperoxidase staining within these ducts 6 . However, pilar differentiation has also been suggested based on microscopic evidence of abortive hair follicle and keratin cyst formation 4 .…”

Microcystic Adnexal Carcinoma: A Case Showing Eccrine Duct Differentiation

“…In difficult cases, immu‐nostaining for CEA has enabled the pathologist to distinguish between similar histologic entities, such as syringoma and desmoplastic trichoepithelioma 14 . Previous investigators have demonstrated immunoreactivity for CEA in lesions of MAC 15 . Immunohistochemically, only the ductal structures manifest CEA; the pilar structures are predictably unreactive for this marker 11 …”

Syringoid Eccrine Carcinoma

“…Goldstein described “islands of basaloid keratinocytes often containing horn cysts and abortive follicles … embedded in a desmoplastic stroma.” 4 Another prominent pattern has been described as dilated cysts and branching tubular structures; tadpole‐shaped epithelial islands may also be present 5,14,15 . The ducts are usually filled with an eosinophilic material and are most frequently lined by two cell layers.…”

Microcystic Adnexal Carcinoma of the Scalp

“…Treatment has included local wide excision, radiation alone, 10 excision followed by radiation, 1 and Mohs surgery 6–8 . Of 15 patients reported by Cooper et al, 2 9 (60%) had one or more recurrences after initial surgical excision.…”

“…Two of the 6 patients (33%) reported by Goldstein et al 1 had recurrences after treatment. Three cases described in the literature were treated with Mohs surgery 6–8 with one case having a recurrence 2 years after treatment 7 . Of the remaining cases that were reviewed, there is insufficient data regarding recurrences.…”

“…Sweat gland differentiation has been a consistent feature of MAC based on light‐microscopic evidence of duct formation and evidence of CEA immunoperoxidase staining within these ducts 6 . However, pilar differentiation has also been suggested based on microscopic evidence of abortive hair follicle and keratin cyst formation 4 .…”

Microcystic Adnexal Carcinoma: A Case Showing Eccrine Duct Differentiation

“…In difficult cases, immu‐nostaining for CEA has enabled the pathologist to distinguish between similar histologic entities, such as syringoma and desmoplastic trichoepithelioma 14 . Previous investigators have demonstrated immunoreactivity for CEA in lesions of MAC 15 . Immunohistochemically, only the ductal structures manifest CEA; the pilar structures are predictably unreactive for this marker 11 …”

Syringoid Eccrine Carcinoma

“…Goldstein described “islands of basaloid keratinocytes often containing horn cysts and abortive follicles … embedded in a desmoplastic stroma.” 4 Another prominent pattern has been described as dilated cysts and branching tubular structures; tadpole‐shaped epithelial islands may also be present 5,14,15 . The ducts are usually filled with an eosinophilic material and are most frequently lined by two cell layers.…”