Skin nonmelanocytic tumor

Adnexal tumors

Sebaceous glands

Nevus sebaceus of Jadassohn


Editorial Board Member: Viktoryia Kazlouskaya, M.D., Ph.D.
Ronan Knittel, M.D.
Nima Mesbah Ardakani, M.D.

Last staff update: 26 January 2023 (update in progress)

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PubMed Search: Nevus sebaceus of Jadassohn

Ronan Knittel, M.D.
Nima Mesbah Ardakani, M.D.
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Cite this page: Knittel R, Ardakani NM. Nevus sebaceus of Jadassohn. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/skintumornonmelanocyticnevussebaceus.html. Accessed February 6th, 2023.
Definition / general
  • Nevus sebaceus of Jadassohn (sebaceous nevus, organoid nevus) is a hamartoma that is histologically characterized by a complex and abnormal proliferation of epidermis and adnexal structures
  • Clinically manifests as a congenital, yellow-orange mamillated patch / plaque with alopecia typically occurring on the scalp and face
Essential features
  • Hamartomatous proliferation of epidermis and adnexal structures that commonly presents at birth as a single yellow patch of alopecia on the scalp, becomes verrucous during childhood and puberty and shows variable enlargement during adulthood (due to development of a range of often benign and seldom malignant tumors)
  • Unusual anatomical presentation and appearance as well as rare association with systemic syndromes (often with neurologic and developmental abnormalities) can occur
  • New genomic data suggest that nevus sebaceus may represent a mosaic RASopathy, often originating from a portion of skin with HRAS / KRAS mutations; this further explains the rare association with other developmental syndromes and intralesional growth of neoplasms
  • The most common types of secondary neoplasm include syringocystadenoma papilliferum, trichoblastoma-like tumor, tricholemmoma and sebaceous neoplasm
  • Development of malignant neoplasms (mainly basal cell carcinoma) in nevus sebaceous is a rare phenomenon (< 1% of lesions in a large series) and almost always occurs during adulthood
Terminology
  • Organoid nevus; though sometimes used as a generic term for the group of cutaneous hamartomatous lesions (see epidermal nevus)
  • Nevus sebaceous; a common misspelling combining the Latin term nevus sebaceus with the English equivalent term sebaceous nevus
ICD coding
  • ICD-10: Q82.5 - congenital nonneoplastic nevus
Epidemiology
  • Present at birth or develops in early childhood, with a prevalence of 0.3% in newborns
  • F = M
  • Affects all races and ethnicities
  • Very low rate of malignant transformation, estimated to be ~0 - 0.8% (CMAJ 2019;191:E765)
  • Can be associated with the following syndromes:
    • Phacomatosis pigmentokeratotica
    • SCALP syndrome (sebaceus nevus syndrome, CNS symptoms, aplasia cutis, limbal dermoid and pigmented nevus with neurocutaneous melanosis)
  • Up to 19% are associated with a secondary benign lesion (J Am Acad Dermatol 2014;70:332)
  • Reference: Calonje: McKee's Pathology of the Skin, 5th Edition, 2019
Sites
Pathophysiology
  • Nevus sebaceus is now considered as a mosaic RASopathy with postzygotic somatic mutations of the Ras protein family, mainly due to HRAS and rarely KRAS mutations, in a section of the skin
  • RAS mutations are also present in secondary tumors in nevus sebaceus (e.g., trichoblastomas)
  • Reference: Calonje: McKee's Pathology of the Skin, 5th Edition, 2019
Etiology
Clinical features
  • Clinical appearance of the lesion can change over time
    • In infancy, nevus sebaceus is usually a smooth hairless patch
    • During puberty (under hormonal influence), it can undergo rapid growth becoming more verrucous with tightly arranged yellowish waxy papules
    • In adulthood, further enlargement can occur due to the development of intralesional neoplasms
  • Nevus sebaceus, often in the form of a giant lesion involving large areas of head and neck, can be associated with a range of ophthalmic and neurologic anomalies (nevus sebaceus syndrome); seizure and neurologic anomalies have also been reported as part of epidermal nevus syndrome (CMAJ 2019;191:E765, Pediatr Dermatol 1999;16:211)
  • Linear and zosteriform presentations have been described
Diagnosis
  • Usually clinically suspected and diagnosed
  • Skin biopsy may be required for confirmation or assessment of secondary benign or rarely malignant neoplasms developing in the lesion
Prognostic factors
  • Generally, nevus sebaceus will follow a benign course
  • Incidence of development of malignant neoplasms (e.g., basal cell carcinoma) in nevus sebaceus is extremely rare (< 1%); a significantly higher rate (up to 20%) reported in some older studies is likely due to misclassification and inclusion of trichoblastoma-like tumors (J Dermatol 2016;43:175, CMAJ 2019;191:E765)
Case reports
Treatment
  • Generally safe to observe
  • Surgical excision as a cosmetic procedure or to remove a secondary neoplasm
  • Superficial procedures such as shave removal, dermabrasion or laser resurfacing are typically unsuccessful due to incomplete removal of the lesion (Am J Clin Dermatol 2015;16:197)
Clinical images

Images hosted on other servers:

Yellow-orange plaque with alopecia

Soft elastic, painless formations

Newborn cerebriform nevus sebaceus

Scalp vertex lesion

Gross description
Microscopic (histologic) description
  • Well circumscribed and complex proliferation and alteration of epidermis and adnexal structures that often changes with age
  • Prepubertal lesions are broad with primitive hair follicles and markedly decreased terminal hairs (hair follicles are usually vellus)
  • Sebaceous glands can be increased or decreased based on the age and associated hormonal effect and can show an abnormal distribution and configuration; they can also be located higher than normal in the dermis without connection to a hair follicle and with direct opening onto the epidermal surface
  • Additional features are variably seen and include:
    • Increased acanthosis, papillomatosis and basal epidermal melanin pigmentation
    • Presence of an inflammatory infiltrate
    • Ectopic apocrine glands (up to half of cases and occasionally dilated)
    • Anomalous ductal sweat gland structures resembling eccrine hyperplasia
  • Secondary neoplasms occur, namely trichoblastoma-like tumor, tricholemmoma, syringocystadenoma papilliferum and sebaceous gland neoplasm
  • References: Int J Dermatol 2016;55:193, Calonje: McKee's Pathology of the Skin, 5th Edition, 2019
Microscopic (histologic) images

Contributed by Ronan Knittel, M.D. and Sara C. Shalin, M.D., Ph.D.
Abnormal epidermal / pilosebaceous alterations

Abnormal epidermal / pilosebaceous alterations

Abnormal pilosebaceous units

Abnormal pilosebaceous units

Abnormal sebaceous glands

Abnormal sebaceous glands

Anomalous sweat glands

Anomalous sweat glands

Epidermal acanthosis / papillomatosis Epidermal acanthosis / papillomatosis

Epidermal acanthosis / papillomatosis


Ectopic apocrine glands

Ectopic apocrine glands

Abnormally configured apocrine glands

Abnormally configured apocrine glands

Sebaceous hyperplasia

Sebaceous hyperplasia

Syringocystadenoma papilliferum Syringocystadenoma papilliferum

Syringocystadenoma papilliferum

Trichoblastoma like tumor

Trichoblastoma-like tumor


Basaloid proliferations

Basaloid proliferations

Syringocystadenoma papilliferum

Syringocyst-
adenoma papilliferum

Basaloid buds

Basaloid buds

Immature sebocytes Immature sebocytes

Immature sebocytes

Apocrine glands

Apocrine glands

Virtual slides

Images hosted on other servers:

Nevus sebaceus

Nevus sebaceus

Molecular / cytogenetics description
Videos

Nevus sebaceus in 5 minutes

Nevus sebaceus

Nevus sebaceus with associated benign hair follicle tumors

Nevus sebaceus (not SebaceOus!)

Sample pathology report
  • Skin, scalp, excision:
    • Nevus sebaceus (see comment)
    • Comment: The sections of scalp skin demonstrate a well circumscribed broad area of epidermal and adnexal proliferation. The lesion is characterized by marked epidermal acanthosis, papillomatosis and hyperkeratosis overlying lobules of hyperplastic and abnormally configured sebaceous glands. There are dilated apocrine glands in the dermis with a superficial dermal lymphoplasmacytic inflammation. There is no evidence of an associated neoplastic growth or malignancy in the material examined.
Differential diagnosis
  • Epidermal nevus:
    • Often clinically presents on the extremities, trunk and neck as linear lesions following Blaschko lines
    • Histologically similar epidermal changes but without sebaceous gland alterations
    • Mesa sign (i.e., the tips of the epidermal papillations are flattened)
    • Normal dermis, usually with no associated adnexal structures
  • Sebaceous hyperplasia:
    • Increased sebaceous glands, usually with no primary epidermal changes
  • Seborrheic keratosis:
    • Unusual diagnosis in children / young adults
    • Some overlapping epidermal changes without adnexal / sebaceous alterations
    • Presence of keratin horn cysts and squamous eddies
  • Acanthosis nigricans:
    • Usually in flexural areas of the body, particularly the axilla
    • Associated with an underlying metabolic disorder or malignancy
    • Hyperkeratosis and papillomatosis but mild acanthosis and no dermal inflammation or adnexal / sebaceous alterations
Board review style question #1

A histologic image from an excisional biopsy from the scalp of a 17 month old child is shown above. What is the most likely diagnosis?

  1. Dilated pore of Winer
  2. Nevus sebaceus
  3. Sebaceous adenoma
  4. Sebaceous hyperplasia
  5. Seborrheic keratosis
Board review style answer #1
B. Nevus sebaceus

Comment Here

Reference: Nevus sebaceus of Jadassohn
Board review style question #2

An incisional biopsy from the scalp of a 2 year old boy was performed; the histology is shown above. Which of the following alterations is most likely to occur in the lesion during puberty if not completely excised?

  1. Development of secondary malignant neoplasms
  2. Enlargement due to sebaceous gland hyperplasia
  3. Epidermal atrophy
  4. Spontaneous regression
Board review style answer #2
B. Enlargement due to sebaceous gland hyperplasia

Comment Here

Reference: Nevus sebaceus of Jadassohn
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