Panfolliculoma pathology

Authors: Dr James Landero, Dr Ben Tallon, Dermatologists, Skin Dermatology Institute, Tauranga, New Zealand. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. September 2018.


What is panfolliculoma?

Panfolliculoma is a benign neoplasm of follicular differentiation that was initially described by Ackerman et al. in 1993. The morphological characteristics of panfolliculoma are similar to those of trichoblastoma, but it shows greater follicular differentiation. 

Panfolliculoma is a very rare tumour, therefore incidence data are lacking. There are fewer than forty cases in the literature.

What are the clinical features of panfolliculoma?

A panfolliculoma usually presents as a neoformation or a slow increase in growth, resembling other lesions, such as basal cell carcinoma, infundibular cyst, and trichoepithelioma. Clinically, it presents as a solitary cystic tumor in the head or trunk up to 3–4 cm in diameter. 

How is panfolliculoma diagnosed and what are the histological features?

Panfolliculoma is diagnosed histologically by the presence of differentiation in all parts of the hair follicle — infundibulum, stem, and bulb/papilla (figures 1–4). The lesions are well circumscribed, and lack cellular atypia. Within the cellular components are granules of trichohyalin (figure 3), pale/clear cells of outer root sheath epithelium, and abortive hair shaft formation (figure 4).

They have been subclassified into 3 main variants: nodular, superficial, and cystic (figure 1), with an additional case that presented with sebaceous differentiation. 

Panfolliculoma

Immunostaining

While not typically needed for the diagnosis, cytokeratin 903 and CK 5/6 stain the tumor cells, whereas Ber-EP4 labels the germinative cells but not the follicular papillae.

What is the differential diagnosis for panfolliculoma?

Panfolliculoma differs from trichoblastoma by the presence of differentiation toward all elements of the follicle, including cystic structures containing corneocytes. Matrical differentiation is less conspicuous than it presents in matricoma.  

What is the treatment for panfolliculoma?

Panfolliculomas are considered benign tumours and are treated by simple excision.

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References

  • Patterson, James W. Weedon’s Skin Pathology, 4th edition. Ch 33, p919. Churchill Livingstone, 2016. Print.
  • Marini M, Starck F, Duhm G, Baldrich MA, Magariños G. Panfolliculoma a case report. Arch Argent Dermatol. 2006; 56: 71–3.
  • Shan SJ, Guo Y. Panfolliculoma and histopathologic variants: A study of 19 cases. Am J Dermatopathol. 2014; 36: 965–71. PubMed
  • González-Guerra E, Requena L, Kutzner H. Immunohistochemical study of calretinin in normal hair follicles and tumors with follicular differentiation. Actas Dermosifiliogr. 2008; 99: 456–63. PubMed
  • Neill B, Bingham C, Braudis K, Zurowski S. A rare cutaneous adnexal neoplasm: Cystic panfolliculoma. J Cutan Pathol. 2016; 43: 1183–5. PubMed
  • Harris A, Faulkner-Jones B, Zimarowski MJ. Epidermal panfolliculoma: A report of 2 cases. Am J Dermatopathol. 2011; 33: 7–10. PubMed

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