Case 18

M75. Excision of mass on scalp. Clinically SCC.

The best diagnosis is:

A. Pilomatrical carcinomaB. Adnexal carcinoma NOSC. Metastatic squamous cell carcinomaD.Primary squamous cell carcinoma

Case 18

M75. Excision of mass on scalp. Clinically SCC.

Case 18 M75.

NOTE: UNUSUAL PATTERN OF IN SITU CARCINOMA

Excision of mass on scalp. Clinically SCC. The best diagnosis is:

PC2a. Male 85, mass on scalp. CK5, p63 positive.

Answer C. metastatic squamous cell carcinoma (of lung)

Primary sites of origin of skin metastases:

• Breast carcinoma (female) > lung carcinoma > colorectal carcinoma > metastatic mucosal SCC from head and neck

• Less common – gastric carcinoma, renal cell carcinoma, ovarian carcinoma, oesophageal carcinoma, other carcinomas and sarcomas

• Children – neuroblastoma, rhabdomyosarcoma

Clues to a metastasis - Clinical:

• Site: – scalp is the commonest site for cutaneous metastases

other than breast carcinoma (anterior chest)

– neck (primary head and neck carcinomas especially SCC) and face. Trunk less common.

– often close to the internal primary malignancy (& locoregional skin in melanoma) e.g. Carcinomas of intra-abdominal origin metastasise often to the anterior abdominal wall & umbilicus (Sister Mary Joseph’s nodule), ovarian carcinoma - perineum.

National Specialist Dermatopathology EQA Scheme 2017 case U337

• Female 88 years. Skin ellipse excision, scalp.

• Skin tumour scalp. No other history available.

National Specialist Dermatopathology EQA Scheme 2017 case U337

• Female 88 years. Skin ellipse excision, scalp.

• Skin tumour scalp. No other history available.

• Diagnosis: metastatic carcinoma

National Specialist Dermatopathology EQA Scheme 2017 case U337

• Female 88 years. Skin ellipse excision, scalp.

Skin tumour scalp. No other history available.

Case 18NSD EQA Case U337

National Specialist Dermatopathology EQA Scheme 2017 case U337

Diagnostic categories: Popularity: Score :1 Metastatic carcinoma 2.55 REMOVED2 Porocarcinoma 2.22 FROM3 Neuroendocrine carcinoma / metastasis 2.20 SCORING4 Basal cell carcinoma (+/- basosquamous) 0.985 Sweat gland carcinoma/cutaneous adenoCa 0.576 Squamous cell carcinoma (+/- basaloid) 0.267 Other diagnosis 0.568 Poorly differentiated carcinoma 0.66

Other diagnoses :Sebaceous carcinoma (x4), trichilemmal carcinoma (x2), trichoblasticcarcinoma, pilomatrical carcinoma (x3), No response, synovial sarcoma, melanoma.

Inapproritae case (multiple).

Original report : Metastatic carcinoma. (Subsequently found to have large cell neuroendocrine carcinoma of lung.)

Clues to a metastasis - Clinical:

• Age: Elderly patients (not a very helpful clue!)

• Sex: Female –

metastatic breast carcinoma accounts for 69% of cutaneous metastases in females

Clues to a metastasis - Clinical:

Clinical history:

• Always check if unusual clinical findings or unusual histological features

• check for history of previous malignancy

Clinical presentation:

• cluster of nodules, but often solitary nodule

• often rapidly growing and large

• Breast – sclerotic areas on anterior chest wall, erythema

Presentation of metastasis – many mimics:

• cyst

• pyogenic granuloma, hemangioma

• papular eruptions

• herpes zoster eruption,

• Rapidly infiltrating plaques, alopecic patches

• Cellulitis, erysipelas

Hussein MR. Skin metastasis: a pathologist's perspective.J Cutan Pathol. 2010 Sep;37(9):e1-20

Clues to a metastasis - Histopathology:

• Well-circumscribed nodule

• Presence of necrosis or haemorrhage –

“dirty necrosis” in colorectal carcinoma

• Lack of connection to the epidermis

• Lack of in situ component

• Unusual pattern of in situ component

Primary squamous cell carcinoma –attached to epidermis

No connection to epidermis:metastatic SCC

No connection to epidermis:metastatic SCC

Primary SCC of larynx

Male 82 solitary nodule right post-auricular region

no connection to epidermismetastatic SCC from previous primary SCC skin of neck

Clues to a metastasis - Histopathology:

• Multifocality

• Vascular invasion

Unusual pattern of in situ carcinoma –think epidermotropic metastasis rather than primary in situ carcinoma

Unusual pattern of in situ carcinoma – focal

Solitary circumscribed nodules – can be primary or metastatic carcinoma or primary benign adnexal neoplasm

Solitary circumscribed nodules – always have metastasis in differential diagnosis

Male 57 solitary circumscribed nodule on trunk

Pitfall!Nodular hidradenoma – common but has variable morphology:

Mucinous metaplasia not adenocarcinoma

Growth pattern and glandular/ductal morphology not typical for primary carcinoma?

think metastasis!

Metastatic adenocarcinoma of pancreas

positive for CK7, CK20, CA19-9negative for WT1, CDX2, p53

Immunohistochemistry for suspected metastasisor to exclude metastasis:

If any of the clinical or histological features are unusual for a primary then consider immunohistochemistry for metastasis

• need to choose an immunohistochemical panel based on the histopathology and the clinical features.

• dependent on immunophenotype of specific primary or metastatic tumour

• Consider panel to include most common cancers:pancytokeratin, CK7, CK20TTF-1, GATA3 (breast, urothelial), oestrogen receptor, PAX8 (females) PSA (males)

Case 18: Differential diagnosis:pilomatrical carcinoma

Areas reminiscent of pilomatricoma but frankly carcinomatous (rare)

Case 18: Differential diagnosis:adnexal carcinoma NOS

Primary skin adnexal neoplasms:• usually p63 and podoplanin (D2-40) positive • follicular lesions are usually also CK15 positive and • ductal lesions are normally also basal cytokeratin (CK5, CK14, and

CK17) positive unlike most metastases.

• therefore p63, D2-40, CK15 and CK5 may be helpful in select cases

• Positivity for all 3 of p63, D2-40, CK15 = good evidence for primary skin adnexal carcinoma

• but not definite evidence for a primary origin • correlate with morphology and clinical features.

• Liang H, Wu H, Giorgadze TA, Sariya D, Bellucci KS, Veerappan R, Liegl B, AcsG, Elenitsas R, Shukla S, Youngberg GA, Coogan PS, Pasha T, Zhang PJ, Xu X.

Podoplanin is a highly sensitive and specific marker to distinguish primary skin adnexal carcinomas from adenocarcinomas metastatic to skin. Am J SurgPathol. 2007 Feb;31(2):304-10.

• Plaza JA, Ortega PF, Stockman DL, Suster S. Value of p63 and podoplanin (D2-40) immunoreactivity in the distinction between primary cutaneous tumors and adenocarcinomas metastatic to the skin: a clinicopathologic and immunohistochemical study of 79 cases. J CutanPathol. 2010 Apr;37(4):403-10.

• Mahalingam M, Nguyen LP, Richards JE, Muzikansky A, Hoang MP. The diagnostic utility of immunohistochemistry in distinguishing primary skin adnexal carcinomas from metastatic adenocarcinoma to skin: an immunohistochemical reappraisal using cytokeratin 15, nestin, p63, D2-40, and calretinin. Mod Pathol. 2010 May;23(5):713-9.

p63, podoplanin and cytokeratin 15 positive in most primary skin adnexal neoplasms and

negative in metastatic adenocarcinoma

Primary skin carcinoma –follicular/trichilemmal

Primary skin carcinoma – follicular/trichilemmal

D2-40 (podoplanin) p63

Male 62. Skin nodule on neck

P63 negative podoplanin (D2-40) negative

Growth pattern and glandular/ductal morphology not typical for primary carcinoma?

so…• Check for previous history of cancer• Report your concern “The diagnosis is uncertain; could be a

primary or secondary epithelial neoplasm in the skin” • suggest full examination of patient• may require radiological investigation eg CT scan